Is love preferable? For me it is. But as to the original question, I don't think it's enough to make any relationship work, really, except maybe family (but I think even that isn't very true, because keeping a family connected or "together" is just as hard as any other relationship. And, just like any relationship, sometimes just because you love eachother doesn't mean it's healthy or good).

(Healthy) relationships take work, communication, trust, lots of other things that help foster and sustain the love.