Hi,
I don't know enough about bipolar to say if there is a connection but I have recently been preliminarily diagnosed with either Bipolar II or Cyclothymia (by my GP - awaiting psychiatric assessment) and also suffer extreme and unwanted obsessions with men - if I know them only very slightly or if I don't know them at all (but never someone I know well) so perhaps I can help.
I have always considered my obsessions with celebrity men or men from my past that I didn't/don't know well as fantasies of the "Knight in Shining Armour" variety. It is revealing that your dreams are about him "saving" you. I imagine that I would be a better person if I was just with so and so, it feels to me (particularly with celebrity/successful men) that I could be successful and, in my imagination, more "me" as a naturally "supposed-to-be-successful-person" (whether this is true or not). I frequently fantasise about them "finding me" at a vulnerable moment - when I'm incredibly sad or in some form of trouble (frequently rape or other violent fantasies) and being a)naturally able to understand and give me the answers I crave, and b) able to take away the pain and/or danger.
Does this sound anything like you?
I tend to see these obsessions as nothing to do with the man in question. Just as people with eating disorders are obsessed with food but their condition really has nothing to do with food/weight at all. (On a side note have you ever suffered an eating disorder? I have recovered from years of disordered eating and consider my new obsessions to be a replacement for those ones).
As I say, these obsessions are likely nothing to do with the man. He is there only as a "symbol" of something you crave. This does not necessarily mean that you believe this man can give you something that your husband can not give you, but rather that you imagine he can give you something you cannot/or have not yet, given to yourself - happiness, stability - you feel unable to "save" yourself and crave a "knight in shining armour" to come along and do it for you.
If any of this seems true to your situation perhaps it would be best to analyse what thoughts and fantasies you have about this man - what does he do/say to you? Could you really do this things/strive for these things yourself? Remember that it is highly unlikely that the man in question can save you or help in anyway. Unfortunately it is ultimately down to you to do this. Although it may be helpful to seek the advise of a professional.
As a last note, I do not think that this indicates that you don't love/respect/cherish your husband in anyway. I don't think you are being disloyal or should feel guilty. I think these sorts of obsessions crop up in all sorts of people under mental distress, not just those with bipolar, and it is nothing but a coping/defense mechanisim. A way of escaping your less-than-perfect reality. If you agree, perhaps you could explain this to your husband and reassure him that you would never act on this unrealistic obsession.
As you mention you think of going to this man's house when mania, perhaps try to set up some sort of method of stopping yourself from doing so in preparation. Perhaps leave a note for yourself, or a reminder of some sort, somewhere prominent, or anything else you can think of, to try and communicate to your mania-self - just in case you have a severe episode and feel it is "right" to express your feelings to this man.
Just remember that your feelings are not real, they are not love. They are a symbol of your own desperation to escape the turmoil your illness has brought upon you. Try to work, with medical practitioners perhaps, on managing your illness and helping yourself feel better. I'm sure your obsession will naturally fade away and disappear if you can find more satisfaction in your everyday life.
Hope this helped!