<human>: So I've(17m) been dating this girl (18f)for about 3 months(we've been best friends since I was 11 or 12) and I seem to have a problem where I start thinking about what she's done in her past relationships/unwillingly imagine what could have happened. (shes a virgin btw but images of her past boyfriends getting past 2nd base, which has happened creep, into my mind and occasionally her having sex with them but I know that hasn't happened.) that just bothers me a lot. 
I know she hasn't even had sex before but anything she's done with people just bother me. Is it weird?

Also she's mentioned that she's masturbated to taylor lautner and channing tatum a lot. This also bothers me.

When I say it bothers me, it doesn't make me mad or anything. It's kind of frustration, some sadness, and just a generally unhappy feeling. How do I get over this? It's something I'm going to have to deal with later in life when the people I date will have had sex in the past.

Can you provide a brief overview of the text?
<bot>: I(17m) keep thinking about my girlfriend's (18f virgin) past relationships and imagining what they've done(up to 2nd or 3rd base) and she's masturbated to famous people. It bothers me.