I think in both cases the "why" is a million little things. Some are rational and obvious, some are emergent and illogical. I'd suggest the audience needs to see some of those little things happening from w/in the perspective of the admirer. Especially the things that surprise and baffle them.

True, and I think there's often an element of the loved one having qualities that the lover lacks to some degree, that they're amazed and delighted by. Showing these things is revealing about both people.