I think it boils down to the meaning of the word trust. If you have to verify, you lack trust. By the way, I’m not arguing with you, I’m just explaining why I think that phrase doesn’t really make sense.

But most people also aren’t actively trying to fuck others over. Life is not a zero-sum game where someone has to lose in order for another person to gain.

I never really understood this phrase. Verifying that someone is on the up and up literally means you don’t (fully) trust that person. Otherwise there’s no point in verifying.

If I’m reading your post correctly, your brother had sex with two women you were dating. What the hell? If I were you, I’d rethink my relationship with him because that’s a line you just don’t cross. Incredibly disrespectful toward you and a very immature thing to do.