I’m pretty sure this was on PBS tv as part of an independant film series.
It’s perhaps an hour long, from the mid-90s, before he was cast into Law & Order Special Victims. He is a great guy, well-liked, engaged to be married.
He feels compelled to share his deep secret with his fiance’– which is that he is an alien. She thinks it’s an elaborate prank, then gets angry when he won’t admit to it. so finally he does say it’s a joke. I think she shows him the door., breaks the engagement. He then goes to her parents to try to get her back, tells the father the same alien story.
The thing about this is that his elaborate story sounds plausible with the details he provides, and in the end the viewer wonders– what is the truth.