I'm on my 4th partnership. I'm ashamed that I don't seem to have what it takes.
This stood out for me, Sylvie. Where is it written that we have to get all of this right when we're 18?
I went through four long-term (several-year) relationships before meeting the man I eventually married. From each one, I learned something about what was, and wasn't, acceptable to me.
Talking to a counselor -- which I'd highly recommend -- helped me to dig through my own patterns, figure out what I'd been doing, and what needs I'd been trying to fill, and how to meet those needs in healthier ways. I attribute my current ability to choose healthy relationships to that inner work done.
Have you done this? Would you consider it, if it would help you to make intelligent, rational decisions now and (if need be) in your next relationship? It was much easier to explain why I had to leave a relationship when I'd fully talked it through with a professional......clarity is so freeing and strengthening.