How Can someone stay Happy after realizing no one loves you?
You simply just have to decide that you are capable of being loved and returning love in return.
What makes you think no one loves you?
It is not possible for no one in the world to love you, and if they don't, you just have to fucking love yourself.
When you understand that no one, not even your closest friends or family owe you their love, then you will live a happy life loving yourself and being the best of you.
There is more to life than love.
Find it, dig it and you will definitely find love.