I'm new here, too.

I can relate to the way you describe your actions in relationships, because I do the exact same thing. In general, I'm a very courteous, kind, and thoughtful person. But when it comes to relationships of any kind, not just romantic, I act so crazy that I'm actually embarrassed for myself when I look back at my actions. Two of my jobs involve helping others with problems, and I've been told, formally and infomally, that I am very good at it. Despite being rational and caring when it comes to others, few can match the finesse of my self-abuse. Like you, I need to stop sabotaging everything because I feel I don't deserve love or happiness.
I hope this forum is a valuable tool for both of us to work on these issues.
Peace and Blessings