There is nothing more bittersweet and heartbreaking than a character who is deeply in love with another but entirely convinced that despite their current romantic relationship (established or not) that they won’t get a happily ever after because they aren’t good enough and the person they love will realize that and leave them but they aren’t bitter or angered by this idea but calmly resigned. Like they love that person so much they’re okay with just being a placeholder for someone better, as long as they can stay by that person’s side despite believing one day they’ll be replaced.