When in doubt, love the one you’re with. And if that doesn’t work, hire someone you like.
We all have to work with people. Even solos (in any industry) have clients. Someone is paying you to do something for them. That is how we make money. I need not give an economics lesson here. The point is simply this: life is too short to work with people who annoy you and make your job difficult.
Most people at some point in time have worked in an office, and 99.9% of the time there’s at least one person in that office that just rubs you the wrong way. If there’s only one, you’re really lucky. Keep that job for as long as possible. But if you are in a position to hire your partner/assistant/whatever, then you need to interview the hell out of them.
Historically, my interviews have lasted no more than fifteen or twenty minutes. That’s probably not long enough to get a real feel as to whether or not you can work well together. (Let me specify that I believe there’s a big difference between someone you like and someone you work well with.) There’s nothing wrong with taking the interview out of the office and grabbing a cup of coffee (or even a beer).
I know there are a ton of questions you’re not allowed to ask in an interview, but that doesn’t mean there aren’t a bevy of questions you can ask. Chat. Talk about their work philosophy. Discuss how they manage work loads and stress. Are they willing to come in early, work late, and weekends if it becomes necessary? You can gather a lot of information about an applicant’s attitude and personality.
When interviewing for a position, take the opportunity to find someone you enjoy. After all, you’ll probably spend more time with them than with your family.