If you found out your boyfriend was texting another girl?

It's nothing, seriously. You're thinking way too much about it. If he was cheating on you or thinking about dating that other girl, why would he let you look into his phone and leave it around for you to see? So he has a friend who's a girl, what's so wrong about that? My boyfriend has friends who are girls, and I let him talk to him. In fact I trust him enough that I don't even snoop through his phone. You're being paranoid about it. You're only problem is that you aren't learning how to trust people well enough. He's clearly have been trying to show that he can be trust worthy. And he probably only told you she stopped texting him because he didn't want you to be worried all the time. He has the right to talk to whom ever he wants.