Went through bf notifications..

So I went through his notifications b/c I don’t have his pw. He left his phone in the car for about 30 mins. Didn’t see too much of course, but I saw a message from a lady saying “how has your day been” so they must of had an ongoing convo going..I’ve never seen her msg before on his notifications. I suspected he has been talking to someone else, he kept trying to assure me he was not. But, BEEN THERE DONE THAT with prev men and their always lying. I told him I’m never wrong when I have a feeling and he said this time I am wrong..And what makes it harder is he’s older than me so sometimes I feel he wants someone closer to his age. These past few weeks have been rocky. We usually see each other on Saturdays and we didn’t the last two because of arguing and that made my suspicion raise even more.