I agree physical attraction is something both sexes desire. There are plenty women complaining about this too (especially those whose SO wishes them to stay in shape while letting themselves go). Both he & his wife created this problem. She by creating & presenting a "different person" to attract him. He when he did not communicate to her early in the relationship "looks" were vital to the longevity of his attraction & again when he did not make it clear when she started to slide when they got engaged. If this a deal breaker for him & it sounds like it is, he really does need to go to counseling with her to see if they can resolve this. If not, then they have to decide if they want to stay in the marriage, be in an open marriage or be unhappy. Benefits behind her back, well he thinks he has problems now. What about unintended circumstances e.g the wife finds out, he or outside lady or both fall in love, it falls apart/possible career damage, his shifting attention lead her to stray.