I’d argue that that isn’t worse than cheating, not by a long shot, unless other details are omitted. If it’s your own personal view based on oreterences, though, it’s different.
The Bible, for example, prescribes no sexual idolatry and immorality, only sex within officially pair bonded, witnessed, wedded individuals of male and female. It’s a sin to galavant and prance about, get a little feely at the 11th grade prom, to look at underwear mags with lust, and about a zillion other things.
remember that, folks