Looking through his phone

Kristie • My friends call me Keek . I was diagnosed with PCOS when I was 17. I am now 24 with a 1 year old baby boy and a 1 month old baby girl 👩🏻🧔🏼👶🏼👧🏻💕
Is it wrong to Have the password to your significant others phone ? When is it a problem and why ? And if you feel there is nothing wrong in having access to your girlfriends / boyfriends , husband or wife's phone ..  tell me why . We are struggling in our relationship with access to phones . What goes too far, & what is acceptable