i like reading manga and watching anime with lesbian characters and relationships, but none of the series i like typically have romance as the main focus, so most of these recommendations will be more plot/character driven, even if the relationship exists
futari escape is really fun, it's a slice of life about a manga artist living with her unemployed girlfriend and the hijinks that ensure from trying to "escape reality" together. the relationship is on the down low but they are canonically partners!
mobile suit gundam: witch from mercury centers around two lesbian leads. their relationship development is also low-key but they get married by the end. please look for the content warnings
the madoka magica side story, magia record, again has an all-girl cast and lesbian subtext. the mobile game archive has a lesbian relationship in canon text.
akuma no riddle is an older anime that centers on teenage undercover assassins from different groups competing to kill a single girl in their class. the protagonist ends up falling in love with her target and vows to protect her. please look for the content warnings