TeafortheWin is right.
Co-dependency. And inexperience in some cases.
Those were the two main reasons for me staying with someone 7 years longer than I should have.
I never knew any better (inexperience). I didnt think I could find someone better (co-dependency). I was terrified about my errors in judgement. Before my ex I was in a rather disturbing relationship.
I find it hard to acknowledge out loud all the reasons why but I do deal with it in head.
When I met my ex... and because of all that prior stuff I'd been through, I thought he was the best thing since sliced bread. I didn't know any better.
It was only over time, after he'd suppressed my hobbies and passions, coerced me into sex and made me feel like utter shit, that I realised that this was not normal either. I was a shell of who I once was with this man and he liked that.
It was incredibly liberating to finally break up with him. But the years before, I had wanted to, I just lacked the courage. Because I didn't want to be alone and because I didn't want to get into a relationship with someone worse.
I'm happier within myself now. Made peace with certain issues. Because of this, I don't fear being on my own anymore. I'm with my OH and DS now but the prospect of being on my own (whatever the circumstances) no longer terrifies me.