Funny enough, it also essentially causes Mal to fall in love with you if you're on the poly path (which requires not being in a relationship with her at that point). I'm pretty sure the points you get from it are actually required to get the poly ending.If MC does that on the Mallory path, it causes her to fully fall in love with MC.
If MC does that on the open relationship path, all else being the same, she's like 'cool I guess; not really feeling it though so I'll fuck your brains out and leave to try to find someone better. thanks for saving my life, and my bff's life, and giving me hope and teaching me how to love. byeeeeeee'