It's obviously not irrelevant for two reasons, one practical one moral. The practical one is that you don't need to 'spill' secrets to a spy. Having one around you in private means you can be bugged, blackmailed, have your means of communication compromised and so on. It makes you vulnerable by definition.
replySecondly if he's willing to lie to his wife and family he's obviously willing to lie to anyone for much less. It tells you something about the character of a person, how can anyone trust a cheater?
Arguably, cheating is now a normal every day part of society. Approximate 2/3rds of people have been cheated on in USA. Much higher in Asia. The sex industry in asia is absolutely massive and it’s primarily for married men. In Japan, only 65% of people say cheating is morally wrong.
replyBut it’s usually don’t ask don’t tell, not explicit lying.
To give a specific example, I’m currently traveling in Vietnam, and an entire floor of my allegedly “5-star” hotel (the most expensive in the city) is reserved for prostitution. This is a smaller city with almost no foreign tourists. The rest of the hotel operates as normal, with a fancy breakfast served everyday 6-9am.