<human>: Can you succinctly summarize the text in 1-3 sentences?

I am studying abroad in Australia for the semester, and three months ago got together with this girl. Everything went extremely smoothly, and we have both been very happy with each other. I know it has only been a few months, but I was really thinking this could last.

Now for the problem that I have been having. Over the past few weeks, I have started to lose affection for my SO. After a lot of thought, it kills me to admit that I believe the reason to be that my SO had started gaining weight. Now before you jump to conclusions, I want to stress that this is not just a sex based relationship. I really share a connection with this girl and she is as perfect as is humanly possible. At the beginning of the relationship, I was starstruck at how beautiful she was, and her appearance has barely changed from her recent weight gain. She has expressed that she is unhappy with it, and I know she is trying to change it. That being said, I can't control what I am feeling. Was I really just into her because of her looks the whole time, or have I simply come to take her for granted? 

I am really struggling with this. This is my first relationship, and I really don't want to believe that the only thing I was after the whole time was her body. Our semester abroad is coming to an end in two weeks, and after that we will be on opposite sides of the US for a month. In other words, I need to decide within two weeks whether or not the attraction was real, and whether or not I should break it off with her. I have discussed this with her and she has been extremely understanding, almost adding to the pain I am feeling due to the fact that I may break her heart in the coming weeks. I want to stay with this girl, but I know it wouldn't be fair to her if we stayed together when I didn't love her as much as she loves me. I need an outside perspective. Please don't go off about how I am a horrible person and only care about looks - I have already beat myself up more than enough thinking about it.
<bot>: Starting to lose attraction with my SO because of her body, but I want to be with her. Was it just lust the whole time, or should we stay together?