As a proud member of the diagnosed bipolar team for 33+ years, I don’t recognise what you describe amongst bipolar symptoms.

But, as Mickey sez, if you’re concerned that you may have any sort of mental illnesses, see a doctor soon.

I lived with depression — and no self-esteem — for sixteen years (hospitalized for 3+ years). It sucked. I mean like it badly sucked. You don’t want to experience that kind of crap. Hence the need for a shrink/doctor.

Those suspicions? Speaking, again, from my experiences, I never suspected my partner of cheating. I bought the stories of night-long sessions to meet early-morning court deadlines. It was only after she dumped me, for a co-worker, that I found out about the vast extent of her indiscretions.

Now.

I hope that your suspicions don’t prove to be true. Do you have reasons to be suspicious or do you just have a gut-feeling? Even if the latter, I don’t think that rises to the heights of delusion (such an odd word; such a strange place!).

If only because of your depression, I’ll reiterate the suggestions that you see a shrink/doctor. Low self-esteem, I think, accompanies depression. If you can, I would set aside concerns about your partner’s fidelity just now and pour your efforts into yourself and your own wellbeing.

My opinion.