Agreed. The film should have catapulted them all to movie stardom. I guess it was just too risky (gutsy) for the time in which it was made, the very conservative 1980s. We should also mention that Dame Wendy Hiller has a supporting role in MAKING LOVE.
P.S. I remember one of the networks aired the film a year or two after it was in theatres (before the home video market exploded and cable TV became what it is now)...and there were a lot of complaints from angry viewers who felt the movie with its daring subject matter did not belong on primetime TV.
As the years go by, "Making Love" becomes more and more pertinent.