Isekai Shoukan Sarete Kita Seijo-sama ga "Kareshi ga Shinda" to Naku Bakari de Hataraite Kuremasen. Tokoro de Sono Shinda Kareshi, Zense no Ore desu ne.

Edward is reborn and lives a carefree life as the third prince of the small country of Astraea. However, his life changes drastically with the appearance of a saint summoned by the goddess. Edward, not his brothers, is chosen to be the caretaker of the saint, whose mental state is reflected in the weather. When he asks her why she is crying, she says, "My boyfriend died." He told her, "That can't be the real reason you're crying. Because that dead boyfriend was me in a previous life!"

A love comedy about a prince and a holy priestess, both of whom were reincarnated in a different world!

(Source: Comic Meteor, translated)