Girlfriend texts guy behind back?

I'm a girl and I know that I usually don't text guys unless I'm interested, you should talk to your girlfriend on where she stands with this other guy.

Why are you clinging to the past? You have the problem, she doesn't. And if you don't trust the person you are dating or seeing, then it's time to move on.

Perhaps you could do your research on Coping with Trust Issues.

You are not her father!

You are not her care-taker or provider.

She does not owe you the decisions to be delegated in her personal life. If she chooses to text another guy, you need to get off your high horse and either accept it or move on.

Your jealousy is going to break up any relationship you have with her or someone else.

If you told her not to do it and she still does it 9/10 she doesn't respect what you ask of her because that is a simple thing to ask of anyone. If you would never do it to her, why can she? And if those past issues relate to this current situation that's a problem.

There was an instance where my boyfriend did the same thing last year, and I specifically told him that what he did hurt me... he did it again and things that were even worse (also without telling me before I asked).

The thing you need to do in situations like these, is have her put herself in your position.

How would she feel if you texted with other girls? How happy would she be about that? Wouldn't she want you to stop? Would she not get upset?

She's being selfish. You're not controlling. Talking with other guys is ok, guys who are not a threat.

Texting with other guys is intimate, she should understand that you don't want that, the fact she hides it from you only confirms that she knows she's doing something wrong.