It is a strawman but giving an ultimatum is also a nuclear option in a relationship and it’s over when the other person said “it’s me or…”, that is the last argument of a failed relationship. Does the first person have an unhealthy habit that they are unwilling to change, possibly, but if you’re trying to change someone to fit your wants and needs then you’re not ever going to be in a healthy relationship.

Maybe you or they change or develop a new habit during along relationship, well then everyone has communicate in a healthy manner and then there’s possiblity of breaking off the relationship.

But I’ve seen this scenario more than once where the partner went straight for the ultimatum and the obvious defense to me would be to not engage or deflect because that’s a Kobayashi Maru.