I'm sorry you are dealing with this. It sucks doesn't it. Not something we signed up for when the relationship began. 1st I think YOU need to call his Dr and explain what is going on and suggest they call him in for a check up. 2nd you need to decide how invested you are in this relationship. Is this something you can deal with long term. I don't know how long you've been dating but you seriously need to think about it because be the other half of a bp is hard. I love my husband madly and I will stand by him until the day I die but we've been together for 18 years. married 13. if I had known and seen before hand I would have had to make tough decisions about if I could deal with it.
Meds help but they aren't foolproof. Many BP's stop their meds when they feel better and the cycle begins again. Until he is comfortable with his diagnosis and willing to lsiten when you see him slipping into an episode it is going to be horribly hard. it isn't uncommon for a person in your position to starting having issues. You MUST take care of you, you can not allow the bp's demons to destroy you. There are support groups and therapist to help you not let him become codependent on you or you on he.
Blessings to you