Post orgasm bad mood

My partner and I have noticed that I have a bad mood for about three days after an orgasm. So bad that she would rather not see me for that period. I try to fight the mood or pretend that I don't feel the way I do, but the feeling is too strong to hide.
I am a 46 year old male. I have been diagnosed with bipolar type two, with rapid cycles. The disorder was induced by Lexapro last year, and although I had a terrible initial time with aggression, assault, psychosis, institutional treatment, arrest and the whole legal mess - I am now quite stable through good management by my partner. I am not on any medication (it terrifies me considering what Lexapro did to my life), and have been well-trained by my partner and avoid all stimulants and depressants.
I have also had a radical prostatectomy three years ago to remove cancer - so I am missing a few key hormones.
We have regular sex and have managed to avoid orgasm for about a month now and I haven't had an episode. But I am constantly horny, becoming frustrated and a little agitated. She also finds it frustratingly difficult as she has to be on guard to stop before I get too close. It makes penetration virtually impossible.
Any advice is welcome.

[Jikan]

Reatding your comment I noticed that you stated that you were not on any medications and that your support was from your partner. If your a rapid cycler you should really talk to a mental health provider about a medication or combination of medications that will not give you bad reactions.  It may take time to find the right combination(I went years), but once it's found I feel your after sex life will be better. Good Luck!

Michael