* Physical or emotional cheating. They strike out automatically. (unless we had children together, then I am willing to work on it)
* He doesn't like my family.
* Too much fighting.
* Too avoidant of fights.
* He's controlling, pushy, disrespectful, possessive, or too jealous.
* Not assertive enough, or too conceding. It doesn't help me when I am interested in knowing what he wants and needs.
* Expects me to take charge of the whole relationship, and is passive. It's like carrying dead weight, I am better off single.
* Holds me on a pedestal, and is unrealistic about who I am (which translates to: he has no idea who I am and he is dating a fantasy)
There are other smaller ones, but they're not really relationship breakers unless they happen all at once.