Boyfriend snapchats other girls

So me and my bf have been seeing each other for about 10 months, officially going out for about 7 months. He’s always snapped other girls since I’ve known him (friends) just sending faces mainly. He’s slightly younger than me (20) and where he is from is where one of my best friends is from and she says it’s a common thing in that area for everyone to know everyone and you Snapchat everyone basically.

Recently he just seems a bit more secretive with his phone, ever since I bring up the other girls. I sometimes look at his phone if he leaves it about , I know this is wrong and basically tells you how much trust I have in him but I don’t unlock his phone, just look at his Lock Screen because all her notifications aren’t private. I seen him Tuesday and he seemed fine but since then was just in a weird mood. Seemed like he was always snap chatting one person as his score was going up 2 all the time and he wasn’t replying to me but it would go up 2. It always seemed like when he did reply to me he was always answering one other person as well constantly. When he came over Friday night I had a peek and there was 2 new girls I’ve never seen before and feel like it’s confirmed what I’ve been thinking. Sometimes I see names that I’ve never seen before and then never see them again and it’s friends that he’s been friends with for like 2/3+ years so I never know what to think, some of these girls live a good 40 miles away as well so it’s not even like they’re close. I don’t know how to bring this up to him as I feel like he’s getting bored of me. Thoughts?