Not in Front of the Children (1982)

Divorced for two years, Nancy Caruthers, asks her new lover, Paul Adams, a medical student, to move in. She has custody of her two daughters, but this new living arrangement prompts her ex-husband, Richard to sue for custody, based on moral grounds. He does not really want the girls to live with him, but his strict religious background will not allow him to stand by and let them be raised in an atmosphere of 'sin.'

Unfortunately the movie Not in Front of the Children is not yet available on HBO Max.