I trust my husband's word more than our friends'.
I wouldn't even say "I heard you're having another relationship" because put that way, it makes it sound accusatory: "I hear you're lying to me". I would put it in terms of "So-and-so said this, why do you think they would believe that?"
My husband's the type of man who has more female friends than male friends, so all the numbers in his phone are either women or family/work-related. He works out of town more than he's home. It would be relatively easy for him to have an affair. But I never would have married him if I suspected he was capable of that kind of deception.
Gralson: my husband (works out of town).
Auto: my girlfriend (lives with her husband Zoffee).
The most dangerous phrase in the English language is "we've always done it this way."