Group me

So I seen in his phone where someone liked a message....the name of the app is group me.....was just wondering wth is that???I've never heard of the app before....by the way I'm the one with the post about him taking too long to go get food at a buffet and he came in and hops in the shower and brushed his teeth when he already did that morning...I couldn't get into his phone because there's a lock on it and I don't know the code....getting very suspicious about him cheating.....especially now that I seen the liked message in his notifications on it...just wish there was a way k could crack that code...I know people say just ask about the cheating but of course he's gonna say he's not I just want to look in his phone and see for myself.....I just want to know so I can take precautions to protect me and my unborn and need to know whether I need to be tested again or not....and give myself the respect I deserve and leave his ass if need be