You need a dose of self-awareness IMO. I always thought this came naturally to everyone but have been rectified here on this board and learned that a therapist is really helpful to aquire this skill.
Why? Well you need to learn how to separate yourself from the bp, and in so doing, learn what is bp and what remains independent of bp.
Me for instance I used to love my bf euphorically when hypo (they are now dysphoric).Gawd it was beautiful, love on steroids I tell ya! But when I wasn't hypo, I still loved him to bits, the bp just wasn't amplifying that particular emotion anymore.
IMO, I don't think bp can cause fake feelings. Unless I'm completely psychotic/ delusional, I don't see me falling inlove with Hitler.
Sure when hypo/manic, we may increase our "type range" if we struggle with hypersexuality and promiscuity, but that still doesn't go under the falling inlove catagory.
How bp can conjure up fake love is beyond me, because at its core, love is the appreciation, trust and acceptance of another, which in turn inspires specific emotions. Love is not a passing mood, its is rather a state of being.
If someone has fallen inlove completely "fakely", and I mean inlove today, "wtf did I see in you" tomorrow, and it was not a case of delusion or sex, then I digress, and also apologize for my uneducated opinion and underestimation of bp's powers.
My opinion on your situation is this though;
Maybe when you get used to the "inlove on steroids" feeling you mistake the "normal inlove" range for falling out of love or not real love at all because of the aforementioned steroids experience...
Its all about awareness and striking a balance at the end of the day, and I too have both a bp and bpd dx, so I know this isn't a simple goal to achieve , but like I said, help from a T would be beneficial at this point.
Good healthy relationships are possible, don't become disillusioned