<human>: Can you provide a brief overview of the text?

We have been dating for a very long time. Marriage has been talked about sometime in the distant future once our life is in order, but not until. 

There is no rush on that front. Since the beginning of the relationship, I have always felt that I might want something else, but perhaps due to the comfort of it all I never acted on that feeling. I am also absolutely terrified of making the wrong decision. There are times when I'm certain I'm in love with her, and times when I'm not. It's very difficult to even imagine my life without her, though.

I am interested in other women. I have never cheated, and never could. However, I feel breaking up with someone for another person is a very bad move. I honestly have no idea if I'm falling out of love, or if I'm just terrified of the commitment, or if it's something else altogether. I really need some outside perspective on this. It is the only relationship I've ever had. One of the hardest things to think of is all the memories. There are so many good ones, and I'd be throwing everything away.

We live together, and I'm worried she would have nowhere to go. I also know that she is absolutely certain we will be together forever, which is another thing making this difficult. I don't want to break her heart, it would devastate her. I do feel somewhat unsatisfied with my life, but that could be for many different reasons. Anytime I think about traveling, or bettering myself somehow, I feel that I'd prefer to do it alone. 

I don't know what to do.
<bot>: Long term relationship, don't know if falling out of love. If I ended it, it would devastate her. It is difficult to imagine my life without her, yet I find myself questioning if I'd be better off.