Hmmm.... I could handle kisses and cuddles only, depending on how long the relationship was... I desperately want children when I'm older, so I would not be able to handle not having sex with the man that I wanted to be with forever, not only because it would be frustrating and the physical closeness of the relationship would not be there, but I would have no chance to have children of my own.
I would also feel as if the guy was not attracted to me, which would be a hard thing to handle... Someone can go out with a person considered 'ugly' by society, but love makes them attractive in your eyes, so given that premise, and the fact that I don't necessarily think that I'm overly ugly, I would worry about the level of love between said guy and I.
Sex IS an important factor in relationships, we are biologically structured to want to have sex. As has been said before, it isn't the most important thing, but it is another way of showing your love.