10 Points: Do I have reason not to trust him?

[Tamera Hill]

There are some things people just want to keep secret. Maybe he's planning a surprise for you, or maybe his friend just messaged his something incredibly stupid/ offensive. As for why he got so mad when he asked, he probably was just tired of you asking all the time. The fact that he cried with you and tried so hard to reassure you is evident that he still does truly care for you.
Just stick with being his loyal girlfriend, and if things continue maybe eventually sit down with him and talk about it. (Of course, don't force him to.)
Don't worry, though--time reveals everything. He isn't the only fish in the sea.