Seto is a super-coward, and so is Iori. We don't really know how much Iori likes him, just that she does. She's given mixed signals throughout.
Izumi is pretty sweet. Stopping by a shrine on the way to or home from school every day to pray for Seto's success isn't obsessive, it's very caring. She isn't stalking him or anything, it's just a religious well-wish. Not any different from a Christian including someone in a nightly prayer.
The point is, that she cares about his happiness, and wants to help him, even if she gets nothing out of it. She definitely cares about him more, but that isn't the only deciding factor. Seto clearly likes her, but he loves Iori, even if she's much worse for him.
Him being a coward and not rejecting her right away may work out... something tells me that manager person calling is going to have bad news for Seto x Iori.