In a normal relationship, you should have some kind of interaction with your partner’s friends. You don’t have to be their food friend, but you should at least be aware of their existence. There’s a saying, “If you haven’t met their friends, you aren’t their girlfriend!” This is still applicable for marriages as well. If your spouse is cheating they may want to keep their social life and married life separate. They may also not want to have their friends feel pressured to maintain their deception. You should be very alarmed if you don’t know any of your spouse’s friends.