Kool_lampshades's manga / #Manga(2)

Daughter of duke and fiancee of crown Prince has her fiance stolen from her by her sister. So she sacrifices herself as a bride to the fabled "dragon king" (a totally sensible action to take). Turns out though, that the dragon is real. And he takes her on as a bride. He goes on to usurp the king of a neighbouring country, and they become the king and queen if said country. They plan to overtake the FL's home country, as they were really shitty towards her. The romance between the 2 MCs is a slow burn.

Typical girl and bitchy bully isekai'd into world. Our girl has glasses that make people ignore her. She's ignored even though she's the one with holy power and not the other girl. She gets taken care of by commander of second order of knights, and POS prince only cares abt the girl after they found out the other girl was not the goddess.