If you don’t trust your partner, don’t be with them is it. The justifications range from “I just wanted to be sure” and “if nothing’s there, what’s the big deal then?” and they are absurd. If things are at a point in the relationships where you are going to knowingly violate the privacy of your partner, it’s already over. Once the phone is always upside down or never out or grabbed right away then you already have your answer with that pattern. No need to look, you know what you will find.