Douluo Dalu 2: The True God King - Chapter 371: [DD2]:

The story revolves around Charles Karino, a Levaamu Empire mercenary aerial pilot who mans the twin seater reconnaissance seaplane Santa Cruz. One day, he receives a preposterous assignment: to fly solo over 12,000 kilometers of enemy waters to protect a girl named Fana del Moral. Fana happens to be the next in line to the empire’s throne and a girl possessing beauty “equal to 5,000 beams of light.”

This is a standalone book. There’s another series under the name “To Aru Hikuushi e no Koiuta” (Love Song for a Certain Pilot) set in the same world, but in a completely different place and with different characters.

– Ulrezaj @ Mazui

Adapted to anime as “The Princess and the Pilot”

Easily cowed and bullied, she was the useless, ugly woman with no talent in medical skills. Supported by millions, he was Tianning’s most respected duke with the power to move all under Heaven. On their wedding day the bridal sedan was carried to the front doors, but the Duke of Qin’s gates were shut tight.