I am looking for the name of what I think is a French film possibly from the lates 70's early 80's.

The film is about a sickly young boy who is sent to a health farm/spa to recover with his mother. The son develops a close relationship with his mother and slowly gets better.

Both look forward till when the father will come to pick them up from the spa. The night before this is to happen, mother and son go to a restaurant. the mother gets a little bit tipsy and ends up in bed with the son.

The next day, father picks them up and life goes on.

My recollection is very sketchy.

I do not think this film is "La Luna" which is Italian and which stars Jill Clayburgh. "La Luna" was about the sons heroin addiction and how the mother "saved" her son.

Hope someone can help.