Is he secretly flirting with her

My bf got let go from his job of 3 years early January and he’s always had his former boss/trainer on fb. The past 5 days she has liked/reacted, and commented on several of his post in which she has NEVER DONE before . When I asked him about it he said since she was his boss she couldn’t interact with him outside of work and now she finally can . I’m like if that was the case why even have her on fb at all when they worked together . So I ask if they’ve been talking or texting cuz he got let go a month ago so why all of a sudden is she in his mentions and he’s like “why?” And that’s not all He also “accidentally” un add me on fb but won’t accept my friend request back . Here’s the txt ....I’m pretty sure they are talking but do you think it’s more than old coworkers ? Cuz why the secrecy. I’d get it if she liked him but as his boss she couldn’t act on it THEN and now she’s trying it but if they just “friends” he could just say that . Right ?