Welcome, @June08, and thank you for posting such a helpful and thought provoking question!

I would encourage him to read up on bipolar disorder. You might want to refer him to a couple online website descriptions. Something like Mayo Clinic's page and also Wikipedia. Perhaps many wouldn't think Wikipedia should be a recommended source, but I actually found it to be more descriptive than most others.

Another suggestion would be to tell your boyfriend symptoms to look for in you. For example, "If you notice me talking a lot faster, perhaps louder, in a disjointed way, overly excited or irritable, aggressive, making peculiar statements or being abnormally paranoid, then I might be exhibiting hypomanic/manic or mixed episode symptoms." Or, "If I seem to withdrawal, seem sad/melancholic or crying for no major reason, morose, etc, then maybe I have depressive symptoms." Also, let him know what he should do in such cases (draw your attention to it, suggest you contact your doctor, know it is not your "usual" behavior, etc.). A potential partner will also want to know that you actively seek and accept treatment. A person who doesn't may be someone they'd want to avoid.

When you have been together long enough to really see a possible commitment, there is also a good book by Julie Fast called "Loving Someone with Bipolar Disorder". It's well regarded and known by bipolar experts. I even met her (heard her speak) once.