Divorce is so common. Do you date a divorced guy? Chances are the ex-wife will always be part of the equation, a bond like that either has emotional or legal ramifications.
Children. As you get older the odds of children being involved increases, something which some find attractive but others do not. My personal opinion is not, for my own reasons an suspicions. Not because the issue of children needs a huge commitment, and because it keeps the ex more involved, but because of my own perceptions.
Hobbies. We all have our own hobbies an activities, and I believe it's good to have time apart, but if he enjoys something you have no tolorence for then it's a long road. Chances are by this age he's set and won't change much.
Drinking. Adults often drink, be it a small glass of wine once a month or a few drinks every night, this can be a deal breaker if you don't agree or can't reach a compromise.
Emotional maturity. In high school girls expect to be more nature then the men, but by this age the difference seems more noticeable to me. Maturity can be more important then age, and it's harder to know without investing time now, as you'd think they are more mature but I've learned that's not always the case.
Family values. Do you both want children? Are you close to your family? Is it important to you to spend a lot of time with your immediate or extended families?
We all have life experiences that make us who we are, and the later in life you meet the more developed you will be, and it can be hard to see just the result without understandin how thu got there. It can also mean what you see is what you will have for the next few decades, which can offer a sense of stability. Most of these issues can be overcome if you can find a middle ground and communicate well, but it's fair to have your own list of deal breakers (if I told you mine you'd list me as single forever, but I want what want and it's out there somewhere). Do what makes you happy by watch for the common issues and prepare for them.