[SammyKid11]

Just ask and be honest about why you're asking. Listen, what you're expecting out of her is fidelity and honesty. It's difficult to have that expectation of her without living up to the honesty part yourself. Don't shadowbox with her on this -- your suspicions are not nearly warranted enough at this stage for you to be successful in that endeavor. You can't call her to the carpet on something because you have no idea what, if ANYTHING AT ALL, she's ever done.

It could be that she's been secretive because she's just joined a sorority, and they have some secret ritual crap about the sisterhood, etc. And it could be that she's acting more lovey-dovey towards you because her feelings for you are growing stronger...or it could be something you don't even know about (maybe some of the sorority sisters have made comments to her about how you're da bomb and she's getting clingy and protective because she realizes you're a hot commodity...yeah, probably not, but you never know).

Nevertheless, at the moment you have no evidence and pretty thin suspicions. Some of the "change" you sense in her could be YOUR insecurity with her joining a group of girls you don't know well or that you expect to sour her on your relationship...or your unease with her joining a group through which she'll likely meet a lot of new guys that you fear might take her away from you. Also, have YOU been unfaithful at all? Nothing causes suspicion of cheating like cheating yourself (obviously if you've been cheating, just do the right thing and break up with her).

But assuming you're on the up and up, all you can do is pick a good moment (when you're in private and have some time, not drunk, etc.) and say, "hey baby, I'm a little freaked out. From my perspective, you've been acting a little strange lately. It feels to me like you've been pretty secretive about your time and activities on the one hand...and then on the other hand you've grown more affectionate and romantic with me. While I enjoy the affection, it coupled with the growing secrecy is setting off some alarms in my head. Are you okay? Are we okay? Is there anything going on...or anything that has gone on...that you're not telling me about?"

If, instead of answering those questions, she becomes indignant that you asked at all...that, IMO, is a bad sign. Sure, if you're the insecure guy that's constantly asking where things are then I can see annoyance. But if you're a normal, confident guy who has honestly noticed some things that make you worry and you ask about it one time and she isn't understanding of that and totally reassuring of the fact that nothing is, in fact, going on and that you have nothing to worry about, etc., then I'd say things might be on the wrong track. In MY experience at least (and it's admittedly limited to the relatively few number of girls I've been in serious relationships with), a girl who's done nothing AND cares about you, if confronted in a non-threatening way, wants to tell you she's done nothing because she loves you and doesn't want you to worry unnecessarily. A girl who's done nothing but is ready to be done with you either way...might shadow-box with you or get angry that you asked, ie- allow it to cause huge a drama/argument. A girl who's done something will either come right out and tell you she's done something (because the cheating and then lying about it was weighing her down and she's ready for the relationship to be over)...OR...she'll totally dance around the issue in an indignant way, make the entire issue about the fact that you brought it up, etc.

In short, if you confront her in the right way and you get anything OTHER than an understanding, reassuring woman...you're in a bad boat, one way or another. It means she's cheated on you...or she's just not that into you to where she gives a crap how you're feeling (because worrying that your woman's cheating on you is just about the worst feeling in the world).

But don't be a dicktard...just ask her what's up and gauge her reactions with your ears and your eyes. I assume you play the unmentionable game...if you do so live with any success, you ought be decent at reading people's tells...especially a woman you've been with for 2+ years.

Bottom-line...you can't keep living in suspicion. If you do, YOU'LL F up the relationship before you ever even know whether anything happened. Ask her confidently but calmly and be prepared for the possible reactions she could have and what each reaction might mean for your future.

Also, remember that your girlfriend (and I assume you) are very young, you will likely have MANY significant relationships before you settle down, and even if she HAS cheated on you/wants out of the relationship, you'll probably be better off long-term by getting with lots of chicks until you're REALLY mature and ready to settle down, anyway.

But no reason to think this is necessarily the case. Be the man, be straightfoward...and good luck.