My wife's boyfriend is her highschool sweetheart. They've been fucking on-and-off for 20+years. I in no way feel threatened or intimidated by her relationship with him. Obviously they have great sex, but he's not husband material. She chose to marry me (we've been married 14 years), and not him.
My wife won't even brag that he's bigger or better than me in bed, even though I know his cock IS bigger and thicker than mine.
As she says, it's just "different" with him, and that him and I meet completely diffetent NEEDS/desires for her