Superwolf: "Blood Embrace" part 2

I think I've found a likely candidate, using IMDb's character name search for "Cliff". "Rolling Thunder" (1977), written by Paul Schrader ("Taxi Driver"), has a hero, Major Charles Rane, who returns from Vietnam after seven years in a Viet Cong prison. ("I didn't know when you were coming back or if you ever would.") His wife has taken up with the guy next door. It has a Cliff. The only thing is that the man's voice doesn't really sound like William Devane. (Apparently, Quentin Tarantino named his production company after this movie.)

Okay, now when I Google "rolling thunder blood embrace", I find a page that confirms it. Why couldn't I find that earlier?