One of my friends(18) was in an online relationship with a girl(15) overseas. They were sexting each other for about a year until he broke off contact with her, realizing the mistake he made. He deeply regrets it and is worried everyday that he's gonna get into prison and get registered as sex offender/ predator. It has affected him so much that he has his mental health go down, grades go down and really just a pessimistic view towards his future. It has been more than a year since they broke up. What are the charges he'll face? Laws of which country apply to him? Say he's from Germany and the girl is from the US. Does the Germany or the US laws come into action in this case? What happens when he visits the US and the girl files a complaint? Does the girl face charge for distributing nudes, since he never asked for it and/or pressurized her, and it was the girl who texted him first? He's a second year physics undergrad, and a smart one. Plans on studying in the US if he gets the opportunity, to get his PhD. But is scared for his dear life that he'll into prison for this mistake he made.
I think that there won't be any trouble from Germany, but the US could be a problem if the girl reports the case to authorities. In that case, further details would depend on the state in question.
As far as Germany is concerned, there are two sections in the penal code that could be relevant here:
§ 176 StGB - Sexual abuse of children § 182 StGB - Sexual abuse of juveniles
To make things more complicated, we would also have to take into account juvenile penal law and whether Germany would have jurisdiction in the first place.
1) Jurisdiction: I'm not sure whether this case would fall into German jurisdiction under § 3 StGB as the case could be deemed to be committed in the US. However, in that case, Germany could still assume jurisdiction under § 5 item 8 StGB.
2) Since our guy was only 18, it would be at the discretion of the court to decide whether juvenile criminal law or regular criminal law is to be applied. In the former case, the sentence would be lower (if there is a sentence at all).
But then we still have to figure out whether our guy broke a law in the first place.
So first of all, let's take a look at § 176 StGB:
“Section 176 Sexual abuse of children (1) Whoever performs sexual acts on a person under 14 years of age (child) or has the child perform sexual acts on them incurs a penalty of imprisonment for a term of between six months and 10 years. (2) Whoever causes a child to perform sexual acts on a third person or has a third person perform sexual acts on the child incurs the same penalty. (3) In especially serious cases, the penalty is imprisonment for a term of at least one year. (4) Whoever 1. performs sexual acts in the presence of a child, 2. causes the child to perform sexual acts, unless the act is subject to a penalty under subsection (1) or subsection (2), 3. influences a child by way of material (section 11 (3)) or information and communication technologies a) in order to cause the child to perform sexual acts on or in the presence of the offender or a third person or to have the offender or a third person perform sexual acts on the child or b) in order to commit an offence under section 184b (1) no. 3 or under section 184b (3) or 4. influences a child by showing pornographic images or depictions, by playing pornographic audio recordings, making pornographic content available by way of information and communication technologies or pornographic speech incurs a penalty of imprisonment for a term of between three months and five years. (5) Whoever offers or promises to supply a child for an offence under subsections (1) to (4) or who arranges with another to commit such an offence incurs a penalty of imprisonment for a term of between three months and five years. (6) The attempt is punishable; this does not apply to offences under subsection (4) nos. 3 and 4 and subsection (5).”
Since the girl is 15 years old, this section is probably not relevant. However, to know for sure, we would need to know her exact age when contact started. If she was only 13 years and 11 months and contact lasted 1 year and 2 months, then § 176 might be relevant after all.
That takes us to § 182.
“Section 182 Sexual abuse of juveniles (1) Whoever abuses a person under 18 years of age by taking advantage of a predicament by 1. performing sexual acts on that person or having said person perform sexual acts on them or 2. causing the person to perform sexual acts on a third person or to have sexual acts performed on them by a third person incurs a penalty of imprisonment for a term not exceeding five years or a fine. (2) A person over 18 years of age who abuses a person under 18 years of age by performing sexual acts on that person or having that person perform sexual acts on them for a consideration incurs the same penalty. (3) A person over 21 years of age who abuses a person under 16 years of age by 1. performing sexual acts on that person or having that person perform sexual acts on them or 2. causing that person to perform sexual acts on a third person or to have a third person perform sexual acts on that person, and thereby exploits the victim’s lack of capacity for sexual self-determination, incurs a penalty of imprisonment for a term not exceeding three years or a fine. (4) The attempt is punishable. (5) In the cases under subsection (3), the offence is prosecuted only upon request, unless the prosecuting authority deems there to be a special public interest in prosecution which calls for ex officio intervention. (6) In the cases under subsections (1) to (3), the court may dispense with imposing a penalty pursuant to these provisions if, having regard to the conduct of the person against whom the offence was committed, the wrongfulness of the act is minor.”
§ 182 para. 1 StGB applies only to cases where the offender takes advantage of a predicament. I seriously doubt there's a predicament involved here.
§ 182 para. 2 StGB only applies for sexual acts for consideration, i. e. when money is being paid. Since apparantly there was no payment involved in this case, no problem here and we can go on to para. 3.
§ 182 para. 3 StGB only applies to cases where the victim lacks the capacity for self-determination and the offender is at least 21 years old. Neither is the case here.
Summary: As far as Germany is concerned, there's no trouble to be expected under § 182 StGB. § 176 StGB might cause problems but only if the girl was under 14 when contact began. (You stated that she's 15. This could mean that she just turned 15 but was 13 years and 11 months when contact began.) As far as German law is concerned, it looks like our guy was overly cautious and there was no need to cut contact.
From the US perspective, however, things will probably be different. I'm not familiar with US law but we would probably need to know the state in question.
What are the charges he'll face?
It depends on the jurisdictions involved.
Laws of which country apply to him?
He could face consequences under the laws of his jurisdiction, the laws of her jurisdiction, the laws of the jurisdictions of the companies whose applications and/or infrastructure were used to send the text messages and/or images, or any combination of those.
Say he's from Germany and the girl is from the US. Does the Germany or the US laws come into action in this case?
Yes. That is to say, both countries' laws apply. Consider: would German prosecutors refrain from prosecuting just because US prosecutors are also prosecuting? They might, but they might not. If US prosecutors could prosecute, but for whatever reason do not, German prosecutors would be that much less likely to refrain from prosecuting.
What happens when he visits the US and the girl files a complaint?
Worst case, a warrant is issued for his arrest and he gets arrested and charged.
Does the girl face charge for distributing nudes, since he never asked for it and/or pressurized her, and it was the girl who texted him first?
I don't know German or US law on this topic.
[He] is scared for his dear life that he'll into prison for this mistake he made.
He should seriously consider engaging a lawyer for advice on the steps he should take to minimize the possibility.