My (23/M) girlfriend's (20/F) best friend (20/F) is dating a 15/M and it is emotionally affecting me.

So my girlfriend's best friend has a boyfriend of one year that she met online. It is completely online only since they live in different states (this is the United States by the way). This was fine because I first assumed this guy was 18 or something while my girlfriend's best friend just barely turned 20 and started college. But when I was driving my girlfriend's best friend (lets call her P) she talked to me about him and she told me that he barely started high school and was 15. This just makes me enraged. I shouldn't even care. But it got so bad that I have had two fights about it with my girlfriend. Although my girlfriend knows this is wrong and gross, she still supports P because "it's my best friend" and she "doesn't want to choose sides". Every time P is mentioned, my skin crawls. I've talked to P as civil as I can and she said a lot of things a lot of creepy people and even some child daters say like "He is mature for his age." or "Age is just a number." or "You wouldn't understand our love." and it's just disgusting. I've talked to my psychologist and psychiatrist about it since I have OCD and generalized anxiety. They agree with me. But I just feel like I have to do something when I know there isn't anything I can do. I also feel like that if she stops dating this kid, I don't know if I can be friends with P again. Literally the only "legit" reason she didn't break up with him after knowing his real age is because "he doesn't want to sleep with me." Of course he doesn't because he can't! It's illegal to do so! I asked if P can date around her college but P says that she only gets guys who want to sleep with her only. Lastly, she said "I hope you can realize that this is just meant to be." after I told her I don't want to hear about it anymore. I was advised to ignore her in which I am doing but every saturday she is in a Dungeons and Dragons group with my friends and girlfriend.

​

Is there anything I can do? Even if it is just for the sake of keeping myself emotionally in check?

​

TL;DR My gf's bestfriend is dating a highschool freshman minor when she is a college freshman who is 20.

​

Edit: Grammar.

​

Edit 2: I really have to say. I can't take it. You're right. If I can't convince my girlfriend, then that is not okay and I might have to leave her, as much as it pains me to do so.

Submitted March 27, 2019 at 01:56PM by lionscastle https://ift.tt/2FAzeJc