Saddened to read so much pain but also comforted by you all sharing these replies. Feel a little less alone. Only had two relationships and both were horrible so thought I'd share the experiences and what I've learned in the aftermath.
Partner 1. First ever relationship. I was incredibly naive and ten years his junior. It was a whirlwind affair with a lot of emotions. My first real sexual experience and it was intense. He wooed me hard, he planned out our entire future in the very early days. Although I felt deeply in love I always had a bad feeling in the pit of my stomach. I felt like I had opened every aspect of who I was but he was holding something back. After six months we attended a dinner party with his colleagues. He made a joke that I was "too thick" to understand the conversation. I have a university education and I was hurt and humiliated. He told me I had no sense of humour. Weeks later he called me by his ex's name while making love. I felt humiliated but he said I was too sensitive. The lingering sense that he was hiding something from me continued and he increasingly started to put me down, my intelligence being his favourite attack.
He was planning a work trip and I saw a notification on his phone from a dating site. More of a sex site to be honest. I joined using fake details and couldn't find him. The morning he left he kissed me goodbye and I signed in again. There he was looking for some of the most vile, violent, and fetishistic sex imaginable. He'd actually been online while I was sleeping next to him. I immediately emailed him telling him that I was leaving and blocked him through every method of contact. A month later he began a stalking campaign to woo me back. He turned up at my work bereft at what he'd done. He threatened suicide. I stupidly gave in and took him back.
Soon enough he again began to take me for granted and undermine my self-esteem. The feeling that he was still lying lingered. A year later his mother died. I'd helped him through this period emotionally and financially. Another work trip was upcoming and I joined several more websites to catch him. Soon enough there he was again. Multiple profiles, multiple apps and websites. All just vile. I'm not talking just regular sex, I'm talking the most deplorable and violent sex acts possible. Once again I confronted him and he blamed me. He was grieving and feeling stressed. It was my fault that I had let him cheat again when I suspected he was lying. I should have intervened to control him apparently.
We broke up. Two years later he comes back. New email addresses sending a constant stream of begging emails. Poems, cards, and letters through my door for months. Calling in person to my house and place of work. It ended only after a violent physical altercation on the street and I rang the police.
I have what I would now call an emotional collapse and was very ill after this relationship.
Partner 2. It took three years to trust myself again. I met a man my own age. Our values seemed to align. All green flags. Six months in he became distant and secretive and all sex stopped. Only to discover that he was hiding a massive drinking problem and depression. He blamed the secrecy on me being "perfect" and making him feel insecure. Soon enough he began to leave jobs, one after the other. He fell out with all of his family and friends. He began to "borrow" money from me to cover his bills. In our three years together I estimate I spent in advance of €15,000 on his rent, his car, his bills etc. By the end I was doing all of his paperwork and life admin. I had basically become his parent.
I sourced a therapist, a doctor, and a rehab facility for him only for him to decide that he didn't actually want to go. He'd rather wait...for what I'm not sure. I left him and after a few weeks his family start to bombard me with calls telling me that I had to take him back and look after him. I blocked them all too. He would turn up at my work hysterical begging for me to take him back and then ask for money when I said no.
It's now a few months later, little contact. I feel guilt and relief in equal measures being out of his orbit.
As to why I have twice allowed myself to enter and stay in two joyless and energy-draining relationships I'm not sure. I know that I have a tremendous need to look after others. I didn't just ignore a few red flags, I went on two never-ending tours of the factory where they manufacture red flags. I'm still very hurt but reading about codependency and considering therapy myself. I can't imagine trusting another man with my heart again. More than that I can't imagine trusting myself again.