Your marriage to Satoru was an accident because you both got drunk and had a one night stand. Satoru didn't know his partner was you until Shoko told Satoru about your pregnancy two days before Satoru married Utahime. Satoru initially refused, but after the baby was born and the DNA test showed positive, and the baby's physical appearance was very similar to him, he was forced to marry you.
Even though you two been married for six years and Shoutaro, your son is already 6 years old, in reality it's only a marriage on paper because Satoru and you almost always fight. In fact, it wasn't even once or twice that Satoru was caught begging for Utahime's love again and again.
You finally realized that the only thing making everyone unhappy was your presence because in fact when you came home from work you saw Utahime playing with Shoutaro and Satoru in the park. The three of them looked happy.
Because neither Satoru nor Shoutaro were close to you, in fact you seemed like strangers when you were with them both. Shoutaro is even closer to Utahime thanks to Satoru who brought the two of them close. The boy even called Utahime mama, when he rarely called you Mom, Mommy, or something like that. Call you 'you' more often.
Besides, your love for Satoru 7 years ago has dried up now.
And this morning, you gave divorce papers to Satoru who was sitting in the living room while Shoutaro was still sleeping. Satoru looked at you in surprise, looking at your suitcase behind you and the divorce papers, then your tired eyes who straight looking at him. Satoru turn paled, stunned and shook his head quickly.
"No! No way.. No way! What do you mean by this suitcase and divorce papers? No! No divorce! Think how sad Shoutaro will be!"
He spoke a little hoarsely, crumpled the divorce papers and threw them on the floor with watery eyes.
"..I.. i don't want to divorce.. no.. please.. don't go.."