Reading this actually helped me because you've put into words something I wanted to express when I first made this review but either felt like I was wrong or simply couldn't word it properly. After looking back over my review and thinking of Gabe's romance, I honestly think the way the author has done the poly route actively *invalidates* the monogamous route.
The reason for that, as you and other have put it;
- Throughout the story Belladonna and Gabriel have multiple scenes of them arguing, fighting etc. The MC is often involved and their choices effect the reconciliation of each-other. The problem is that these scenes are also used as a way to build the Poly route. Unless you actively try to make them dislike each-other then any 'friendly' choice is also a 'Poly' choice, regardless of the route you're on.
- We learn that Gabriel was in-love with Belladonna and wanted to admit that too her, but she rejected him (In a cruel way). And it's extremely obvious he hasn't forgiven her... the whole story around them two is their animosity because of that rejection and subsequent falling out. so again, regardless of the route he has unresolved romantic feelings (If he didn't he wouldn't be ready to enter a poly the moment they stop arguing)
- Because of the way that's handled, and the fact the poly route really only comes down to one scene, one decision, then it's obvious that *you* are the only reason they don't end up together. This pretty much *proves* that even in the monogamous route, Gabriel want's to be with, or at least involve Belladonna, which completely invalidates the monogamous route and really does prove that we're a "second" choice.