<human>: Can you succinctly summarize the text in 1-3 sentences?

I don't want to make this too long because it could go on forever but I have recently found some pictures in my girlfriends phone that would lead me to thinking she is cheating on me. 

I found these photos in her private folder so I had to do some snooping around to find it. The picture is of her in lingerie in what looks like a front hall way. But the thing is the front hall doesn't look like hers to her house at all. The doors don't match like hers and the one door handle in the picture doesn't match with any of the ones she has in her place.

I was puzzled so I looked at the info on the picture and it said it was taken at around 10:40pm March 8th 2015. I immediately went into my texts and saw if we had been talking or if I had called her at all. Nope. There was a hole in the conversation from 930pm - 1130pm that night. I checked her texts and her friend had been trying to call but her friend texted back "hey your phone is off, call me when you can!"

I don't want to assume she's cheating on me but I've been cheated on many times in the past and I just come to conclusions of the worst case scenario.

The thing is, her phone has a password on it and she doesn't know I know what it is. I can't bring this up to her unless I have facts that she is cheating.
<bot>: found pics in my girlfriends phone that would lead me to think she's cheating. What do I do and how do I get the facts without her knowing I snooped through her phone?