should you give your phone password to your partner

the password shouldn't be asked for.

you already know your spouse's or your long-term partner's password anyway, you've picked it up somewhere along the natural flow of life, and wanting to specifically ask for their password just to look through their phone is disrespectful too, it's the kind of thing that runs on trust.

wanting to look through their phone out of the blue for no reason would be foolish, in my opinion, but if a moment comes where they start trying to hide their phone, keep it on silent all the time, or get overly tense or panicky when you ask about it, then there's a problem there.

as far as i'm concerned, two mature people know each other's passwords and don't try to sneak in and snoop through it, that requires a certain level of maturity.