I guess I read it differently. The first being the truth and the second the balm for her heart.
It often causes conflict in a poly relationship when someone develops an interest in someone who is mono only and it's not unusual for someone to want to be the primary in a poly relationship. Yes, "spare lover" is a pretty dismissive way to refer someone who is a secondary in a relationship . . . Shadowheart has some rough edges.
And this is why it's all bad. Poly isn't simple. It requires serious consideration and a lot of dialogue to set up correctly. They did none of that. What they did is write every origin companion as mono, wrote dialogue to explain why they're mono, and that's where it ends.
That's why none of them are okay with having a poly relationship with each other. Or open relationship, for that matter. You don't get the choice to even ask for a compromise, it's mono or nothing. That, to me, in addition to the dialogue itself, is more than clear enough to prove that they're all mono.
