The difference between when you predominantly love someone and when you predominantly desire them is that when you predominantly desire them, being in their presence and knowing they don't belong to you is more painful than not being in their presence at all, whereas when you predominantly love them, having them around at all is a joy and not having them around hurts far worse than any minor detail about them not being yours.
Somewhat Wilder Assertion:
It therefore follows that if you look at someone's LJ friends/friends-of lists and find that they never ever under any circumstances put anyone on their friends list who doesn't reciprocate that, this is somewhat unpromising evidence of their usual love/desire balance with most people (or at least with most people on LiveJournal).
(I currently have 29 people on my friends list who do not have me on theirs. It could be argued that I am more prone to making wild assertions when they are favorable to me. :p )