While I agree that love is about more then sex, I do think sex is a part of love.
First of all, if I were to get married, we're talking a LONG time into the relationship, like 5 years at minimum, even then I find the idea uncomfortable.
But most of all, I think I would have trouble distinguishing between lust and love after a while. Like food, sex is instinctual, and being denied something you desperately want for a long time is one of the many pathways to obsession. If the entire crux of our relationship became the fact that we weren't having sex, I may eventually feel pressured into marriage, which would subsequently not last.
The other issue is that I would eventually have trouble being intimate because it would frustrate me so much, as I couldn't do anything to express my love without thinking of sex. For that matter, sex is, for me, an aspect of bonding, and I find it hard to imagine knowing how I feel about a woman until I can, shall we say, look at her just as she is, without hormone tinted shades. When sexual and emotional curiosity is sated, and the only thing that will come out of staying with this woman, is just being with her, THEN I'll know I have something special.
Feelings aren't things we control, to just be wished here and away. I always thought that wanting someone to promise to always feel the same way about you is somewhat wishy washy, refusing own up to consequences and to accept facts of life and human nature. Desiring a quick fix, a potentially and statistically empty promise for something there is no guarantee of having. Further more, I feel that it would be irresponsible of me to make a promise of something I may not even have.
I would avoid a relationship that would require me to compromise so, I think it would just hurt us both in the end. I'd be there if she changed her mind, but I'm not big on gambling blind