When to give up?

Lunch time posting again, yay!
I'm beginning to lose my mind waiting for others to make up theirs. Why are things not as simple as they first appear? I mean, either you want to be friends or you don't, right? It's not a difficult concept to grasp, so why is it being made so difficult? Why the lies? Why the ignorance? I just don't understand at all. Not one single bit, I'm putting in my all to try and make things work as friends, try to get us back to being close friends so they know I'm there for them, but maybe that's the problem they don't wish to be there for me. I get that I'm being an intense person right now, but I've lost so many friends in the past and I've never met anyone as similar to myself as they are, I guess I'm just really scared of losing someone that means a lot to me. At least I do not want it to happen again.

So, when is it time to give up? How do you know it's time to just walk away?