Shigure knew it wasn't enough.
His love for Akito wasn't enough for her to choose him over Kureno. It wasn't enough to make her to love him in return.
Sleeping with Ren was the revenge he sought, yet it wasn't enough to numb the pain of rejection or remove the burden of his love.
He wondered if his plan was enough to break the curse. He hoped that whatever she had inside her and whatever she did, would be enough to free them all of their weight.
But Tohru might not be enough to break the curse on her own.