when happiness turns to sadness

It had been a long time that I'm not as happy as the time when we r together.Just that i force myself to smile n be happy in front of others to hide my sadness.Recently,I met a new someone that could make me smile in a perfect way of sincerity and happiness.There's smthng in him that could change my mind for not having one to having one.At first,i have no feeling for him and just assuming that he is just my close friend.Maybe the main the reason I have feeling for him is that, he is mature and he is the person that could make decsn for himself because he knows what's  best for him.But everytime when I gain happiness in a sincere way,it will be vanish soon.I know,I'm not meant to be happy.My happiness turns to sadness when I get to know he had feeling for smone else and day by day i could feel that he is avoiding me especially whn evrybdy is talkng abt us.In less than 24 hours before,I saw him .....: (
I wish you happy alwys : )