Ikemen Koushaku no Oi o Hirottara, Amai Shinkon Seikatsu ga Hajimarimashita

Marianne, a young baroness mistreated by her stepmother and about to be forced into a marriage she never wanted, escapes from her house. Deep in the forest, she finds and rescues George, a young boy who seems to have lost his memory. Through fate, she becomes George's tutor at the household of young Duke Robert, George's handsome uncle. As Marianne helps raise George alongside Robert, their relationship gradually deepens into something more meaningful and loving. What starts as a compassionate act turns into a sweet "newlywed-like" life, blending romance, family growth, and emotional healing in a warm depiction of unexpected love.

https://www.cmoa.jp/title/319756/