We know Waifu is immortal or reborn with past memories, there was no need to retcon the Husbando into the reincarnation of her past lover, is a cliche we have seen a thousand times and if the author planned this shit we would have seen the signs before so I'm sure he just came up with it recently, now her progressing with her life/leaving behind old regrets gets erased from him being that person.
Caretaker Senko used this storyline too but at least there it was hinted from the start, this mangaka using it is patethic, a sign he was unable to came up with something more original, unique, the plot is not going to get better, bye bye honeymoon, time for some dumb conspirancy or absurd progressing that will make us cry for past chapters.