As far as I can tell, Ana and Christian's relationship in 50 Shades of Grey is based on the following:
1. Their mutual sexual attraction.
2. Christian's abusive need to control his partners.
3. Ana's delusion that she can somehow change Christian.
They don't really understand each other; they don't communicate well, and yet they love each other. Since they've known each other only several weeks as book 1 ends, I opine that they are feeling infatuation, but not love.
Even if they are in love, they don't seem to like each other. By that, I mean that they don't enjoy each other's company, unless they're having sex. I do not have high hopes for this relationship being satisfying for both partners for any length of time.