ugh y do I feel like this

Last night my I felt like my boyfriend was hiding something from me like I was laying down not faceing him and I kept hearing his snap chat notifications goof and every time I turned to the other side he would he put his phone down , I noticed that he was watching a video of him lip singing a really nasty song from a long time ago and it look like he was about to send it and I tried not to look to nosey so I closed my eyes. I always trust him so that makes me feel even worse that my instincts are telling me he's hiding something. We just almost broke up bc one of our friends lied on him about something and I accused him of it , should I ask him about it , or should I try to go through he's phone .