Why do we?

Why do we humans long so much for love?  Love from a child, pet or friend works.  What makes us lovable or unlovable?  Is it right that we are sometimes expected to change from who we are to what someone else wants to make us lovable?   Then if we do that do we lose the self love we must have for ourselves.   Self love sounds selfish but I think you must have it.  Sometimes I don't love my "inner child" enough.  This is when the self doubts creep in and make me doubt that I am "lovable"  This is the point where I tend toward depression,  when my heart hurts and tears flow.  I hope I am lovable.  I've lost family and more family in the last couple of years, my ex in laws and for some reason the only blood family I have left on my Mom's side.  I don't think I did any thing wrong but I'm sensitive about this for some reason.  I guess because the man I thought was the love of my life was able to discard me so easily.  I wish I could ask the questions and get real answers not what he thinks would be the right answer.  I'm really tired of the not you it is me,  it wasn't anything you did and so on.