Is it rational?

Liv
I hope I am wrong, but my boyfriend whom I live with, we have an apartment together, I think he may be cheating. Here's the signs:
He's more secretive. He'll text girls then delete the convos. He won't open certain apps when I'm around that he used to. He got a ride from a girl at work today & was 50 minutes late. He's calling other girls pet names. He gave some girl at Walmart his number. I literally watched him do it. He didn't know I saw. & he's insanely protective over his phone. Didn't used to be. Now he is. He'll take his phone to the bathroom even if he's gone for 10 seconds. I just have a bad feeling. I've tried to be rational. I thought maybe he's just trying to make friends. But it's too friendly & why would he delete the conversations?
I confronted him about all of it. & he had a point for everything.
For the petnames he said he was trying to comfort her. For the girl at Walmart he said he forgot my phone number. For being late he explained why. 
I feel like these are red flags, but I'm not sure if I'm just insecure. 
Thanks❤️