I think I may understand what you mean, esp. about your friend. I had a friend who I used to look at everything they did on Facebook and would get jealous about their positive comments about other people. It's like I could concentrate on nothing but our friendship/pseudo-relationship (I found out 2 years later after he had said over and over how he wasn't interested in me... that he was, in fact, gay - which was a relief to me! It showed it wasn't me that he wasn't into.. but my gender as a whole! haha and we even got closer.. but it definitely wasn't a healthy relationship at all.. definitely hard to explain).