There is crazy, and then there is crazy.
I had a friend who was bipolar. If that is her only problem, bipolar is not that bad. Bipolar means they make big swings from excited and ambitious and energetic to lazy and depressed. It is annoying at times, but livable.
This means that you'd have a girlfriend who will bug you to go for a walk in the park at 4 a.m. because she has so much energy, or you will come home to find that she decided to become a pastry chef, and she is baking a dozen cakes to practice. Then, you take her on a nice vacation to Cancun, and for a couple of days you will fight to even drag her outside onto the beach, as she wants to sleep and be depressed.
If I had a cute girl like that and she was good in every other way, I could live with it. Good nutrition and supplements can go a long way to help people with bipolar, and possibly cure it.
The real crazy to avoid, the ones that others warn you about, are Cluster B. Borderline personality and Narcissistic personality are disorders that wreck lives. Narcissists are much more malicious, but borderlines also tend to be addicts of one kind or another. They are both toxic, and almost never get better. Narcissists in particular get more malicious as they get older. Stay far, far away.