I thought I could make my bipolar husband happy, but it can't be done- what do I do now?

Not your fault. It's his illness you can try to get him into a good psychiatrist etc but if he resist or treatment doesn't help you have to think how you want to live.
Wow, you can't. Your bipolar husband needs to find his own happiness, you shouldn't feel it's up to you to make him happy. Couples counseling and bipolar support groups are places to look for help. And don't forget talking with his doctor to see how you can be a part of the treatment plan. See nimh web site for help: http://www.Nimh.Nih.Gov/health/publications/bipolar-disorder-in-children-and-teens-a-parents-gu.