Does a relationship ever need to be worked on a reciprocal condition?

Does what you received equate to what you will want to give?

Is it because I he/she did this to me and that is why I must do this and that to him/her?

I often feel unconditional about giving to all relationship, and never want anything back in return. But when I chanced upon an incident that my frenz juz left me out of his/her group of people that he/she miss, I realized my name is not in there. I'm not jealous lah, but just felt...felt as if I want something back in return. Or probably want to be in the "top" list.

Am I starting to expect something in return. Oh well, I shouldn't be reading too much into things. I should just let nature takes its course. :(