I'm not sure I have any automatic dealbreakers. I used to, but one by one I met people who disproved most of my assumptions about what I wouldn't be able to tolerate in a relationship.

I thought I couldn't ever date someone with a mental illness, because it would be too much emotional work and they'd end up dragging me down with them. Then I made a friend with psychosis and a history of depression, and he's one of the most easygoing people I've ever met, emotionally and otherwise.

I thought I could never date a cheat, because I'd never be able to trust them. Then I made a friend who was a serial cheater, but he's the one I tell the secrets I don't trust anyone else with, because I know he won't pass them on or judge me for them. And whether it was a dealbreaker would depend heavily on the circumstances, I think, although I've never been in that position so I don't know.

I used to think I couldn't date someone who was very religious, because my outlook on life would be so different from theirs. Then I made a friend who was a Creationist, and she's one of the smartest, funniest, least judgemental people I know, with a really good sense of humour about religion and politics and other sensitive topics - she just grew up with everyone around her telling her the Bible was the literal word of God, and who knows what I'd be like under those circumstances?

I thought I could never carry on dating someone if they were ever violent towards me. And then I had issues with my own mental health and did things I'm now really ashamed of, and I could see how if there were very very exceptional circumstances and it was completely out of character for the person, I could maybe move past it happening once.

Granted, I was never in a relationship with any of these people, but none of the things I mentioned were the reasons. Which isn't to say I'd give everyone a chance - if someone's a cunt they're a cunt, and I'm not going to date them just in case they're secretly nice underneath. But beyond the most obvious things like being an unrepentant serial killer and rapist or something, I'm not sure there's any single factor where I'd say 'no way, never' without knowing anything else about the person.