Maybe I adapted to be more taciturn and take life less seriously a long time ago, when someone told me what I was feeling wasn't valid. There are too many things you think you cannot say because you think it is inappropriate or that your emotions were just too big; they would fill every fibre of your being, expanding and suffocating and pressing against all the corners. You know that others will grow tired of your constant paroxysms of sadness, so you think that keeping mum would be good.
You fear the people you call friends would get sick of your feelings and would stop caring, so you bottle it all up. You just can't share; every other set of words would fuel some form of bitter or spite judgement of "he needs to get over himself." Either way it's unhealthy afterall.
It is selfish to be happy.