I saw messages on my boyfriend's phone that he doesn't love me but won't tell me in person.
Oh no... but why won't he tell you that in person?
I'm not sure, maybe he's afraid to face me.
I know you're concerned about your relationship, but it's not appropriate to look at messages on your boyfriend's phone. Even though you're in a relationship, those are private messages. Talk to him about his feelings about your relationship.
I'm going to talk to him about this. I need to know if he loves me if that's true or not.
This is quite a situation, but you shouldn't have been snooping in the first place. Perhaps that could be a reason why he wants to break up... But you can't ever be too sure so yeah, how about just asking about him how he truly feels about you? It could just be a misunderstanding.