I believe she definitely needs to trust herself more.
Instead of concentrating on HIM and what he did or didn't do, what he is or isn't feeling...she needs to take a deeper look at what she's feeling.
I would imagine when he didn't call, she began to feel insecure, and fearful and uncertain...and perhaps instead of wondering why SHE responded that way, she projected those feelings onto him and made it about him. Ultimately, she was accusing and blaming him for HER feelings.
As soon as a situation arose where there "could" be a worse answer, such as cheating, she jumped on it and accused him...probably to give a reason to why she felt fearful and insecure in the first place.
There is every hope that giving yourself some time and distance to really look at this will give you the answers you need. And perhaps, once you've been able to turn this situation inward and not make it about him, he will be a little more inclined to listen and understand why you reacted the way you did.
But you have to be able to explain it to him first.