50’s/60’s pop(?) film where girl finds brother? kissing a guy in stairwell?

All I can remember is a slim girl in 60’s gear (mini, beads – Susan George / Linda Thorson lookalike) at a party in a flat.
She decides to leave via the back stairs (a circular stairwell?). She sees a guy (her brother?) on the stairs kissing another guy.
He looks up at her and says something to the effect that you have to take love wherever you can find it.

I think I saw it on TV in the 1960’s/1970’s.