I’ve told my sons over and over that few things in life are more painful than to discover that your significant other has cheated on you. It’s like a knife in the heart and will most likely destroy your relationship so don’t go there. But if you do, don’t get caught. Take it seriously. Play your cards like you’re an undercover agent in East Germany in a John Le Carre novel. Which means short-term flings only because long-term affairs are always found out sooner or later.

This isn’t a roundabout way of saying it’s okay to cheat — it’s not. It’s a very cruel and selfish thing to hurt someone you care for and are committed to out of erotic whim. But people are fallible and no one is perfect and a dalliance or two doesn’t have to be fatal. Just be careful.

Massy Tajedin‘s Last Night will play at the Tribeca Film Festval (4.20 through 5.1). Keira Knightley, Sam Worthington, Eva Mendes, Guilaume Canet and Griffin Dunne costar. Tadjedin directed and wrote the script. It’s basically about two couples dealing with temptation, etc.

The only thing giving me pause is that Last Night began shooting in October ’08, and here it is almost two and a half years later. It played at last September’s Toronto Film Festival, but that represents approximately a 20-month gap between wrapping and being seen, and that’s still a little prolonged.