My best ally wouldn't put my realm in such a position of vulnerability without even consulting me first.
Had Phantaria called your bluff, and Morek been forced to punish either Phantaria or Niselur-Libero, who'd be backing that D'Hara-Luria Nova peace treaty? Alice just learnt that Morek was still pledging to militarily defend D'Hara if Luria Nova chose to break it, which she was getting ready to do...
Yea, my best ally would put us alone against the forces of Aurvandil, Phantaria (kinda), Saffalore, Falkirk (kinda), and Luria Nova. Totally. My best ally would also totally usurp traditional 'moot territory to place a foreign-backed non-republic on our doorstep. He'd also create a useless tension among the realms of the region, when really what we'd truly need to is bring everyone back together to KO the weakened states of Aurvandil and Falkirk.
But yea, sure, go ahead and claim that...
I said your best ally. I didn't say a good ally. I just said your best one.
Besides, just because Hireshmont likes D'Hara doesn't mean he agrees with Machiavel on what's best for D'hara. Machiavel is a paranoid racist. Hireshmont isn't.
Yeah sure if Phantaria had called the bluff there might have been an issue. But wait! They didn't! And they weren't going to!
Machiavel betrayed Hireshmont first; he's getting what he deserves by seeing his political ambitions problematized. Besides, D'hara is stronger than it's ever been, and Terran's interposition between D'Hara and Phantaria protects D'Hara from the real expansionist threat: a reborn Terran under Phantarian leadership.