Everyone has regrets, individuals dwell on them differently. Personally I am not bipolar (thought I was but have had too many dr's dismiss it and say I'm just depressed, anxious and bored.) but I have known a fair few people that were. 'Normal' is an alien state to the average bi-polar person, if they aren't peaking at either end of the scale they are usually on their way up or down. What they strive for is balance and will often give up or adopt anything they think will help them acheive it.
Low self esteem is common also in people with bipolar and they will often try to isolate themselves so they can't burden anyone, bring anyone down or hurt anyone they care about.
'People are never perfect but love can be. People waste time looking for the perfect lover rather than creating the perfect love' - Princess Leigh-Cheri from Still Life With Woodpecker.