Well-written and interesting post!

I would say which is more difficult depends on the situation. Certainly if you love someone who is unaware or doesn't care, you are the only one suffering.

On the other hand, if you are aware that someone loves you, and you are an empathetic and caring person, you may feel a lot of guilt and pain over the other person's plight. Feeling that you should love them back, but unable to. Wanting to make them feel better, but unable to.

Which is harder in the second case? I'm not sure.