Yes, it makes sense

Few days before this, you entertained the idea of marrying someone and making her your wife. After all, that was what the society expected from you, which you were eager to fulfill. But as they say, a human mind is very adaptable. Not only you find yourself alright with committing **** with your mother, but also keeping her as a sexual partner with no semblance of responsibility. Besides, you couldn't take back what you did. You already sated your lust using your mother's body and vice versa a few times, each ending with you sowing your seeds inside her. Haruka could already be pregnant from your incestuous unions, so you had nothing to lose. You might as well embrace her.

"I want to make you pregnant,"

"You probably did," Haruka replied.

"True. But when I did it, I didn't know what I know now. Now that I know, I don't want our child to be an accident borne out of our lust. If you're to be pregnant with our child, it's because we want it."

Haruka smiled. "I found my son wanting to assume the responsibility as father to our children flattering, and at the same time arousing."

Every single night, you and Haruka fucked, ending with you filling her fertile womb with your seeds. Every single time, after you're done, you went to the altar in the room, you prayed so that your incestous union is blessed with a child. Without realizing it, you and your mother already became a pair of lover, a couple of man and woman not joined by matrimony, but the basic lust. In the end, both of you got what you wished for, the proof of your lust, the growing child inside your mother's womb.