Could be that Himawari is the actual reason for it? She gets to "live" in some way while Ayane gets reseted one more time, as a sacrifice. Still, if that's the case it's kinda a lenient sacrifice, Ayase keeps her progress with Akira
and make it through the next reset anyway. Okay... at least she is left with the trauma of losing a child, which is not something minor. And since we are on the topic: I don't remember the lengths this was discussed, so it was probably already brought up, but what did you think of the time Maya confronted Ayane about being pregnant? (outside Akira's apartment just before Ayane's first successful reset). Is it possible that Ayane knew she wasn't carrying, not by checking every day but because she knew she simply
can't get pregnant anymore?
Overall, I'm still banking on the you gotta be pregnant (the first time) theory. I don't like this "love" thing because now you have to define exactly what love is. Akira can say he loves Maya, Niki, Ayane, Makoto all at the same time, in my opinion he's just a slut. Unless is defined on his actual idea of love of course (still, it should be defined by the Gods rather than him, I think). Same with trauma, how do you set the bar of a "worthy" trauma? Who's the judge? Io?

. Meanwhile, you are either pregnant or you're not.