My gf has a crush on a guy, any advice? am i overreacting?

I've been in a relationship my my gf for the past seven years. During the 3rd year i had to move away to further my studies and im still away doing so. i travel back home every summer and meet up with her and spend time with each other. she recently took up a job in her country (sept 2013) and since then things have been rocky for us because when she comes home she is tired due to the long hours required at her job (especially since she lives far away). We got into an argument and she told me that there is a guy (who is a foreigner only working temporarily at her job) in the in particular who is a colleague of hers at her job who she talks to and she wonders what'd be like if she is in a relationship with him and how he would treat her. The guy has no idea (according to her) and she just finds him attractive because he looks like me.
Now bear in mind that she just told me this today and before that she went on a vacation with her other colleagues (of which this guy also went). Plus she encouraged her parents to carry her and the guy and another female friend of hers to do some site seeing around the country (because he was curious). She also 'likes' his pics on fb. I've posted a few romantic things on her wall and she doesn't even like them. In addition to this the company that she works for provides transportation after work to do extra curricular activities such as dance class of which her colleagues (including this guy) and herself partake of. ive spoken to her about it and she says that she cant help if he goes to dance class with her and vacations. And at the end of it all she comes home saying that she's tired and just wants to sleep and behaves grumpy. Please note, by nature im a very jealous person. am i overreacting?
Any advice is appreciated.
Thanks.

Even if she's not doing anything physically, she's having an emotional affair. That much is obvious, and it really only leaves you with one question: Are you going to put up with someone cheating on you?

Personally, I don't think it's best for you to remain in this situation... But that's just me because I know that it'll drive any normal person to the brink of insanity constantly wondering if their partner is ever going to stop or what they did wrong to push them to that... The key, however, is to remember this is NOT your fault. You can't stop anyone from cheating on you; they'll do it if they want to and you can't control it. BUT you can control your life and whether or not you're in a relationship with a cheater...

What's it going to be?

I'm gonna say, the minute you left to study in another country, you two became pen pal and not BF/GF. You can't possibly still be in a romantic relationship, when you only see each other during the two months in the summer. This type of arrangement erodes over time because with out proper continuous physical contact, the emotional connection dies off, and this is what has happened. Naturally she has now latched on to this guy, because it is a human need and you can't stop it from happening. She may not realize what is going on, she could be very well confused about what she is feeling...that emotional connection with this guy is very addictive and it's pulling her in. It's like smelling the delicious pie, but not eating it so that would mean you are still sticking you your diet. It isn't cheating if they are not physical, not verbally expressing their attraction to each other and not spending time alone doing date like things. people through their lifetime will have a crush when in a relationship, but whatever happens in ones head is nobody's business.

So what to do. If you want this situation to change, you need to change your situation with her. You need to move back to be with her, if this isn't possible, then it's over....she is doing all the signs of wanting to move on with her life. IMO I don't think you are being fair to her continuing a relationship like this for years. She has needs and you are not providing them. It's no wonder she is drifting away from you. Let her go.

7 years together and you've not even tried to advance this relationship to something more committed and so that you can be together. She's checked out and I don't blame her for any of it except that she keeps you while she does date like activities with him.

Break up with her and give her the freedom to do what she pleases. She's too weak to actually let you go before he commits to her at this point. Soon enough she'll get the courage though by what I've just read.

I agree, let her go. It's only a matter of time she will have the courage to end it.

You guys have only seeing eachother during summer months for the past 4 years? Honestly I don't blame her for doing what she is doing. One would think if you were committed enough to call eachother bf/gf that you would try and see her more often. She's probably fed up with the fact that you don't try and keep that bond between you guys.