She let herself go...

[muffin]

My G/F is has gotten real comfortable lately and gained quite a bit of weight. She has an awesome personality, is loyal to me and can still please me in the bedroom however I really don't have any sexual attraction towards her. I end up having to be drunk most of the time we have sex.

I go to the gym myself up to 6 times a week and try to encourage her to go to. She enjoys yoga so I offered to buy her a membership but she always seems to find an excuse not to watch what she eats and refuses to commit to an exercise program

 

[TheSplat]

One of the toughest situations to deal with in a relationship. You need to be honest with her and tell her how you feel. It will hurt her at first, but it's much better than you being secretly turned off the whole time.

 

[Nutz]

Them letting themselves go is very common when they feel they have you locked in. By demonstrating that they're not on as secure footing as they think it keeps them on their toes and forces them to keep doing the things that you found attractive from the start. IMO the prudent thing to do is letter know she's gained weight and it's having a negative impact on the relationship. If she doesn't like it that you're pointing it out to her, feel free to show her the door. When you do this one of three things will happen:

1) you guys break up for good.
2) you guys break up for a bit, but she comes running back
3) she puts the cake down and goes to the gym.

Believe it or not showing them you're willing to walk is a very attractive thing to do over the long haul (assuming if she stays). It demonstrates you're not needy, not afraid to say what you think, etc.

Now before you say anything, think about the long term results. What I'm proposing is ultimately a win-win for you. Either you guys break up and you get out of a relationship where you're not truly happy, or she loses the weight and you're back to happy status quo. Either way you're better off.