Is my girlfriend cheating?

ok i know what you are going through you just dont want to be lied to i would sit down and talk with both of them and tell her to pick which one either she has devoted herself to you or she has changed and is with the other woman i would talk to them about this and think long and hard because you dont want to worry about what she is doing everytime she is out do you it is just gonna put alot of stress on you and thats not healthy. if all else fails yes i do think that she is having relations and probly not telling you move on if you can  its better.

The situation you describe is fishy.  Whatever you do, control yourself and don't kiss her butt out of fear of losing her.  If there is cheating or even the possibility of it, jealousy only gives power to the new, mysterious relationship.

Here's something you can try:

Make friends with a new, attractive woman, and talk about her once in awhile to see if she is jealous.  If not, it could be a sign.

If there is any way to get the two of them in the same place with you, you can usually read body language and figure out if they are lying or not. 

ok u sound pretty smart you have already answered your own question! take your own advice guy! This girl is not for u, if after 4yrs of being with u as a couple, a mate. And she can just up and do what she is doing and being dishonest with out even caring about your relationship then that alone speakes for it's self! She is sneaky and a cheater weather it be physical or mental. once a cheater always a cheater! If she is lieing to u then how in the hell can she be perfect??? beauty is only skin deep, ugly goes all the way threw!!! I would say back off and watch to see if she notice u are not there any more and if she dont notice then u have your answer.... if u love something let it go, if it comes back to u then it was ment to be if it dont then it was never ment to be... i know corny but true!!  Good Luck...Peace out..

First of all, I think your girlfriend could be just flirting with this woman, maybe not to a point where she would cheat on you, but just in a way we all kind of do with people we admire. She may be in awe of her, just as a lot of people are when they come across someone in a position of power over them. As you said, she's changing her style of dressing and music, probably because she is looking for approval of this woman. In a way she could be somewhat obsessed with her and somehow wants to be like  her (she probably  has reached a high position in something your girlfriend is obviously interested in since she's studying and dedicating time to it). It's most probably a phase that she'll get over as soon as she sees this woman is human and has faults, much like the rest of us mere mortals. This usually comes in a hard lesson from disappointment.

About the love poems, I can't say, since you haven't told us what the woman is teaching her... Is it literature, poetry? Or is poetry just something she likes a lot and your girlfriend is trying to get her approval by showing her her writings? 

The question lies I think if you want to be in the middle of all this, since it seems that her obsession is ruining your relationship? It seems that you are doing more than your part in keeping the relationship alive and she isn't even appreciating it. Heck, I think she's doing everything she can to even sabotage the whole thing you guys have. She probably needs to realize that someone she just met isn't all as wonderful as she thinks and start appreciating what she already has that needs to be cherished. 

Also, if you are giving her too much, maybe you aren't leaving her space to become better because it's all done for her. Start doing things just for yourself and be a bit more independent, that way she can recover the respect you deserve.

Hope this helps? 

I'm gonna be blunt bro, you need to get some balls, thats why she is walking all over you. This isn't even debatable, hell yeah she is cheating, she is practically doing it in your face which shows she doesn't care anymore........ You've got to know when to let go there are many wonderful women out there don't let this one run you into the ground!!!