Do you think it’s good for someone to go through there partner’s phone

Question: do you think it’s good for a person to go through their partner’s phone to reveal they’ve been cheated on?

So I’ll give some examples

Ex 1: married couples

Let’s say they’ve been ten years, and one was cheating on the other for five years. The one being cheated on snoops through partner’s phone and find them sexting different people. They also stumble upon finding out the partner has been hooking up with others.

Ex 2: couples in the dating phase

They’ve been dating two years. One has been secretly chatting up a co worker. Partner snoops through phone, and sees the message but nothing physical has happened yet. A few months later, the partner cheating emotionally tries to plan to meet the coworker to have sex. The other finds out about these plans three days before the meet date.

Do you think them snooping to reveal being cheated on is good so they can leave? Or do you think they shouldn’t be snooping?

I don’t want to hear how you trust your partners and feel no need to snoop. This is about those who have been cheated on, but found out in other ways.