This is exactly what I've been looking for. The cuck doesn't know he's being cucked, he almost certainly doesn't want to be cucked, but it's happening behind his back and it's not clear how he'll react when he finds out. If she has his permission, it's not cheating, which ruins the whole thing for me. This is innocent curiosity slowly turning to insatiable lust, just the way I like it. Beautifully done, with character development that I really want to follow all the way to the end.