In the title of this thread, you are asking the wrong question, IMHO. Not all persons with Bipolar Disorder are the same, as I 'm sure you are not claiming. The better question is: "Is it reasonable for you to expect a normal relationship with this particular man whom you have been seeing?" There are people in very satisfying relationships with partners who have been diagnosed as bipolar. So the answer to your original question is "Yes, maybe. It has happened." But, so what? That's kind of irrelevant to your specific situation.

There are people without bipolar disorder who are impossible to get along with. Then there are bipolars who've achieved reasonably stable, satisfying relationships. So the fact that your guy has this particular diagnosis doesn't give anyone the right to say, "Oh forget it. Nobody can have a decent relationship with a bipolar person. Don't bother trying!" It all depends on the individual. It depends on him and it depends on you. Bear in mind that there could be a lot of other reasons why your relationship with him doesn't work out. He's got problems other than being bipolar. The combination of the bipolar issue and those other problems, taken together, may end up being more than you can deal with . . . or not.

It is reasonable to expect that the future with him is going to be a lot like the past. Base your expectations for the future on that.