After seasons of misunderstandings and one-sided confessions, Rias and Issei finally confirmed their love for one another by episode's end. After Issei defeats Sairaorg in the final battle of the rating game, Rias sees that his new "Queen" upgrade to the Red Dragon Armor is the same color as her hair.

DO Rias and Issei get together?

In Volume 17, their relationship has improved to the extent that despite going out on a date with someone else, Rias chose to believe in Issei and the fact that he will still love her. ... At the end of the volume Issei proposes to Rias, which she tearfully accepts, making her Issei's first official fiance.

Who does Issei really love?

In Volume 22, Rias was there to allow Issei to be promoted to High-Class devil, during the ritual in which she placed the crown on his head, which made Issei a King. Later the two become engaged when Issei proposes to Rias after her graduation ceremony, making her his first bride.