Nice guys don’t even finish

How many of you have tried to be the nice guy in the relationship? What usually happens? It doesn’t end well. And usually she ends it with you. You are left. Wondering what happened. Thinking to yourself I did everything she wanted me to. I treated her well, I compromised I gave up my friends and now she’s not interested in me anymore. She says it’s not me it’s her, but it still hurts the same regardless. What am I to do?