sometimes, being there does not always benefit you. and it's not supposed to, not really. as long as you care about the other person you're willing to lend your happiness to for a while, until theirs grows stronger, able to tend to itself
but you can't let yourself become a doormat.
no matter how much you try to convince yourself that you're being there for comfort, to be a good friend, to show how much you care, you will end up dirty and forgotten and stepped on
stay away from people who treat you like you have a 'Welcome' sign printed on your forehead