I believe the general's thoughts are plain text while Marl's are within a bubble. It's a little unclear in the Japanese version too.
He's getting worried that Marl is constantly improving, which is risking his "certain victory", and decides to inject poison by making up some BS about marriage and releasing Marl and Mikagami.
The guy is a veteran fighter playing mind games on a hot tempered rookie.
Upon a re-read, that makes a lot of sense. Alexandros acknowledges to himself that Marl is a threat to him. But given he's the more worldly fighter in this context, up against a more hot-blooded individual who doesn't have the experience, he's utilizing psychological warfare to maintain that "certain victory" of his.
On another note, I like the different ways in which Mikagami has to win fights. We know he has to win these, so the fun is how he does so. In this case, it's interesting Chris' shield is strengthened by her raw emotions of fear and survival. So Mikagami resorting to a method to change her mood as a way of making her subconsciously more inviting to weaken her defenses is a fun avenue to take here.