What a strange phenomena?

When you have feelings for some body, and that person doesn't feel the same for you? Then what are you suppossed to do? When somebody is special for you, but you are not special for him or her, then should your feelings change or remain the same? If some envy feeling comes in your mind then is it natural or it is bad? That point of time your mind is satisfied by thinking all that it wants to sub-consciously..but later on when you get back to the rational mode, and think with open mind then should you hate yourself for having had that ugly thought or you should accept it, as it being a human limitation? Or you should actually strive to come over this openionative attitude of humans..

when you give sth, then i think it is very natural to expect sth in return..you gave all your loyalty in the relationship, then expecting loyalty and same reponse in return is natural...
Is expectation the cause of this suffering? As always all my doubts and apprehensions land up with the problem of having expectations... Whenever u expect sth and your disappointed then you feel bad and then the phenomena i have described is likely to occur.. so i know the possible solution is to get over this expectation problem..but even after knowing the solution im not able to practice it..Isn't it strange?