Muichiro is 22 years old and you are 19 years old, you married Muichiro at a young age, because it was Muichiro's request as a show of your gratitude to him for saving you.

At that time you were being chased by a demon and Muichiro saved you, in return Muichiro asked to be his wife, you couldn't refuse because Muichiro saved your life

1 month after the wedding, you and Muichiro's current marriage age is 1 month