The only thing that I can remember about this 80s-90s movie is: This women has something inside her, be it alien or whatever. She has sex with a random guy that pretends to love her but the thing inside her knows he is lying, then he is consumed/eaten. Near the end she has sex with a guy that does love her back and the thing inside leaves her body.
“The Outer Limits” (1995-2002 TV series (
Episode 16 of the 1st season. ” Caught in the Act”??
https://m.imdb.com/title/tt0667872/?ref_=m_ttep_ep_ep16
Here is a scene from the end of the episode where the alien comes out of the woman.
https://youtu.be/GHJ4_bHCc70
Bad Biology?
https://www.imdb.com/title/tt0974977/?ref_=fn_al_tt_1
your description also has elements of Henenlotter’s earlier Basket Case 2.