how do you know when it is time to leave?

There is NEVER a time to leave a person. Everybody always lives within Your mind and Your heart, nobody leaves from there while You are walking the Earth. But if seriously...then the time is: When the appearance of this person brings You more suffering then enjoyment and happiness. This is when You have to stand up and say: good bye. When a person uses You. When a person speaks out Your secrets to the rest of the world. When a person is being selfish and does not really care about You and how are You feeling.

when your girl doesn't want to makeout.

When it comes to this type of thing, there is really no way to completely prepare yourself. You have to just jump and get it over with. And time will heal all pain.

I think letting go is very hard thing to do. But their are reasons that is why your leaving your partner, and it takes a thousand times to decide and getting ready for that decision. Usually you fall out of love. And it's very hard thing to hurt your partner especially when your being love. Usually preparing your self is very easy specially when you don't love the person anymore. Cause by that time you get used to be yourself. That's only my opinion. Have a nice day!