Zense de Aishita Hime ga Tensei Shitara Oji-san deshita前世で愛した姫が転生したらおじさんでした; The Princess I Loved in My Past Life is Now a Middle-Aged Dad

A princess and a knight who loved each other but could not be united. They vowed to meet again in the next life, and were reborn. The knight Bartolomeo has been searching for his beloved Princess Claudia for 17 years. When he finally finds her, she has turned into an old man.