Her eyes are a deeper blue

1. Things with Termina went badly. His sibling wants to kill him. And she could. Up until now he's been very casual about his safety because if his body dies he can be put on again. He massively messed up.

2. He missed Hal's play. Getting the theatre and helping Hal has been a huge part of his life he built and he missed it.

3. Hal might want to remain friends, and even trusts him as a co-conspirator, but since confessing what he is Hal doesn't trust him as a person.

4. Teor and Cyd died. He didn't know them, but he deliberately made the choice of team spy because he worried about Wicander and Tyranny's abilities and for the first part of the mission they were completely fine. And when he gets separated from Wick in order to find his sibling who turns on him, Wick murders someone and loses his innocence which Bolaire can perhaps relate to with his line about learning to hate.

5. We know what plowshares are now. He's a plowshare. No one but Mara really acknowledged that, but theoretically if they needed an anchor it could be him. So there's a fear about dehumanizing him and using him as a tool once again. Or the expectation to sacrifice himself.

6. His sibling tried to kill him. Hal doesn't trust him and it can't be the same with him. Demodus is gone. He even says he feels he has no family and before Thjazi brought him into this he did. He had the hope of finding his siblings through the museum. He had Hal's friendship and theatre and family. He feels like he lost it.

6. Thjazi isn't gone. The first time we meet Bolaire he is at Thjazi's hanging and he laughs with relief. It's not just anger or hated. He fears Thjazi. He doesn't want to be under his thumb.

So Bolaire is facing all these things and losing all these things. He is feeling helpless. He's facing consequences of actions he felt were the right thing to do, and as it turns out Thjazi is not facing consequences in death. The person he hates is safe in a shadow.

The person that owed him. Either through blackmail or a more literal sense it doesn't really matter, Bolaire's agency and freewill were cut off after meeting Thjazi.

So that feeling of helplessness and lack of control goes up exponentially.

Of course he's freaking out. Just like how Occtis has a freakout with the seekers about his family and the party's trust in him and all the pressure he's under while facing that he's not alive anymore. Bolaire is emotionally young and is facing his own death essentially. Both the idea of it literally through Termina, but also metaphorically with the Museum Curator. A lot of it isn't about Thjazi at all, but Thjazi is connected to a lot of it which is why Bolaire's outburst is centred on him.