@wakthorweebweeby
They get together in a better way where the 3 child exist.
But the Husband died (likely) in exchange for Rinko life in the same timeline.
Idk how Rinko even managed to be saved but it's likely in acceptance of Rinko that Loves had to be this way in order for them to get together in the end including the 3 child.
Further explanation
1. If they get together the childs won't exist.
2. If they get together Rinko will die
3. They bad to be separated until much later so Kohaku, Hinata, Yukina could exist. Which means A-chan will eventually get married in future.
This lead to that ending where (idk what happened the husband) but they got together (likely living as well) making it a bitter sweet (harem) ending.
@Vmpslushie
I think author forgot about her.
She was certainly mentioned as someone she wanted to see but maybe Rinko mentioned not in romance way.
She certainly exist but she didn't get anything in the ending where A chan, Rinko, Kohaku, Yukina, Hinata get together (may live together as well, if you noticed that there's few sandals and shoes on the floor where they're actually outside the house).
The idea of this manga is great, but rushed and convulted too much with the timelines and the forged rules.
It's hard to comprehend here which is similar to Qualia the Purple.
The first timeline where Rinko met the 3 child is actually the best timeline that is similar to the ending but is likely filled with remorse and regret being unable to accept the fact that Rinko or A-chan were separated.
The fact that she got phone call likely A-chan had to play the antagonist part and was separated with her own child (break up) in court after Rinko took her child which explain Kohaku hostile act against her because A-chan left her child with her husband (later be taken by Rinko) and keep herself away from Rinko. (Knowing that she might kill her if she came too close to her or get together because karma.
Compared to the ending, A-chan likely stays with the husband without breaking up until He died in accident in exchange of Rinko death.
The real unanswered question here is that timeline was affected by both unable to move on hence Rinko death (Traffic Accident) happened again after the husband death when A-chan called Rinko.
So after all the shit both party finally accept everything had to be done else there won't be a happy ending for the two including the Kid who haven't been born yet.
Thus created that ending that is similar to the first timeline except this time there's no more problems (A-chan breaking up, Rinko repeated death, Yukina and Hinata doesn't exist) hence both of them could come together again as family including the A-chan Kids.