Big Girl In The Making

My girlfriend is gaining weight. It's an issue for me. I've busted my butt to maintain a good body for her and I expect her to do the same. She won't go to the gym. She's eating very unhealthy. Plus she smokes.

I've lost a lot of my sex drive towards her and see myself looking at other women at the gym. I'm no cheater, but I have never had the wandering eye til now.

I don't know what to do. I want her to listen to me and cut some weight. That's all I find wrong with her. I know I have my faults and I do everything in my power to fix them FOR HER. I just want her to do the same.