"Nice guy"? In my humble opinion, nice 40-plus year old guys with wives and two children don't cheat with 22 year old girls from work.
That said, I agree that 41, relatively speaking, is not at all "old," but there is, none the less, a rather large age gap between Rupert and Kristen - basically 2 generations. He'd've been out of high school before she was even born.
I also agree that he can look quite handsome. And often these cheating types
are very "charming" so they can have "likeable" personalities. But still, it's just a little too creepsterish to me. I just can't see him as a "nice guy" in light of these circumstances.