Two plus two equals five (I hope)

DigForVictory

OP, please, talk to her.
(Don't mention the phone snooping.)
Otherwise the doubts go on & the fun dissappears and unfortunately it'll be your fault for the doubting. (Founded or unfounded.)

Alpha58

There could be all sorts of reasons for setting up screen lock - the OP has children in the house and which of us doesn't have kids who have used their phones (usually for playing games)? Kids are frighteningly tech-savvy these days.

I'm a man in a similar domestic position, and although it's no consolation to the OP, you are not alone in the upstairs department experiences (or lack of). Don't forget that for us it's a relatively simple business - for women, there are so many emotional factors as well as physical ones that it's not as simple as it is for us.

You've checked the phone once - I would strongly suggest not going down that road again as if she finds out (and she probably will) you are looking at an erosion of trust that it will be very hard, if not impossible to get back. Easiest way? Ask her. Tell her about your concerns and see what she says. You may be pleasantly surprised by her reaction!