Nah, I usually accept that both sides need to apologize, but not this time. He's completely valid in his anger.
To hear that your partner has gone back on the front lines of a war from someone at work rather than directly from them? That must be soul shattering. What kind of thoughts must have been going through his head in his way home? "Did she not trust me? Is there something more going on? Am I not important to her?"
Communication is the single most important thing in a relationship and she avoided it because she's embarrassed? Hell no, she should be more embarrassed by her own actions at this point. It's honestly so aggravating that her apology was so short and seemingly half-assed and HE had to go so in-depth about why he was angry.