The worst part of believing that we are unlovable is that we start acting the part. In so doing, we interact with others in ways that end up proving to us that our belief is true.
We become people who act in ways that are hard to appreciate.
We become someone who is difficult to love.
We go on believing and behaving in ways that reinforce our low opinion of ourself, having no idea that that's what we're doing!
We feel sorry for ourselves for being “unloved victims of an uncaring world” when in reality we are trapped in our own untrue beliefs.