Several sets of people go to a group session to deal with their marital problems. The women speak in the current (as of 1970) argot of needs and validation. The men mumble, a bit bewildered by the entire process, but trying to make an effort to save their marriages. Then they roll and share a joint.
Looking at this movie, I am impressed by the old dictum that men marry the woman they see while women marry the men they can make into the man they want. Or perhaps men are less introspective and until some one makes a point of it, they don't bother to change. It seems significant to me that when the lead couple catches their son with drugs, it is the man who raises the question of whether they need to stop using pot themselves while the woman wants to just talk about it.