A frustratingly not-terrible action thriller.
"A Little Sex" is an entire movie on the subject of fidelity, involving two people who do not seem to care much one way or the other about the subject. That's not to say that the movie doesn't rant and rave about cheating on your spouse. It's just that its tantrums seem borrowed directly from the millimeter-deep emotions of TV sitcoms, where people fight because it's 12 minutes into the half hour, cry because it's 17 minutes into the half hour, and lovingly embrace each other because the half hour Is, at long last, finished with. Everything in this movie happens on cue.
The movie Tim Matheson, the likable stud from "National Lampoon's Animal House," and Kate Capshaw, who sounds like a Shakespearian heroine but comes to us via TV's "Love of Life" and several commercials. They make an attractive couple, and with other characters to play and other dialogue to read, they would be fun to watch. Following their adventures in this movie, alas, is like one of those dreams where they're after you and you're up to your knees in sand.
Matheson and Capshaw are cute Manhattanites who seem to inhabit an elusive New York where every corner is occupied by a friendly greengrocer, and young lovers can run down the street and say things to shock the sweet old ladies who are squeezing the oranges. He works as the director of TV commercials. She's a teacher at Mother of Christ grade school (I figured that out because there are 900 "Mother of Christ" T-shirts in this movie).
They've been dating for two years. Maybe they ought to get married. Matheson's problem is that he is Irresistible to women, who keep seducing him. Capshaw doesn't know that, allegedly. Matheson makes a bet with his brother (Edward Herrmann) that if he gets married he will be faithful to his bride. But it doesn't work out that way, and after Kate catches Tim with another woman, she decides to leave him.