I know the plot. It's about a couple, husband is a doctor, wife met with an accident and slips into a coma. Husband tries everything, but after seeing her hidden things, contacts her ex-lover and asks for help. Wife regains conciousness after visited by the ex-lover and he asks her to marry him but she chooses the husband. She had a daughter with the ex-lover and a son with the current husband.
It sort of sounds like Angel Falls by Kristin Hannah. If that's not it, try posting here: https://www.reddit.com/r/whatsthatbook/
I've seen them find some pretty obscure stuff!