Well, I've not actively looked for a relationship for years (and obviously I'm not looking at all now) but I think the main thing I need is someone willing to invest as much time and effort into our interaction as I am. This is probably another huge reason I don't have any friends; I am extremely high maintenance and require constant attention to feel valued. I'm insecure and have had one too many people I've cared about in the past completely ghost me, so I have extremely high standards for considering someone anything beyond the most casual of acquaintances. Someone who can make me feel like I actually matter to them, and not like a nusiance if I want to talk, is someone I will cherish.
I suppose patience and understanding are both requirements for this, because I regularly need to take breaks from interacting with others (which might seem like a double standard, but I tell people if I'm going away - I have never had anyone tell me they're going to be unavailable or busy for a few days) and it takes a very long time. It took about a year and a half of talking on a daily basis with my partner for me to consider the idea that she wasn't going anywhere, and six months (to the day we first met!) on top of that before feelings. I'm a lot harder to get close to than most people and I'm really not worth the time or the energy, because whilst you'll get my attention, you won't get my affection, and for most people that just doesn't seem to be good enough. So yes. Patience.
Beyond that I'm actually pretty accepting...sure, plenty of things irritate me, but I'm not the easiest person to tolerate either, and I generally don't care about people's personality quirks unless they disrespect me as an individual. I might find certain things...distasteful, but at the same time, I'm not going to tell other people how to think. Your opinions are your business; just don't expect me to buy into them as well and we'll get along fine. Mutual respect is important in any lasting interaction. It seems to be more of a trial for other people than it does for me. xD