I really question that he loves and respects you very much. It is not uncommon for one partner (you) in a marriage to think that all is well in the relationship when, in reality, it is not. Perhaps you are blind to reality, as you knew what he was doing and presumably did not put your foot down to stop this very nasty (and STD dangerous) activity.
It sounds as though he was into persistent sexual adventures, which may well have manifest as intimacy/sex issues between the two of you. In my opinion, few men like to continually date and make many "conquests". He did, which further suggests sex and matrimonial difficulties on the home front. It doesn't seem that he is a believer in monogamy.