Back when I was in my so-called "Cringe Era" I didn't really use love interests for anything but that, somebody for RMZX to lust over/protect or something. Needless to say, it bugged pretty much everybody else that I RP'ed with, well, that and using established characters as love interests.
Anyway, when it came time to start doing Wilypocalypse, I decided against using a love interest at first, since I didn't want to fall into my old habits. But I decided on adding Akai relatively early, though since I didn't want to make her into another waifu thing, I avoided giving her a name or design. That's what led to her being the character she was, I let somebody else create her design and her name. And, after her "helpless girl" personality was essentially overwritten, she became sort of her own character, I did eventually take her out of the story because I didn't want her just hanging around with nothing to do. After her original death I tossed the idea of introducing another love interest, but I quickly scrapped those plans and instead focused on re-introducing Akai into the story, with her trying to do something besides be a cheerleader. This culminated in her breaking up with Josei. I'm not sure whether or not I'll bring them back together or if I'll have them just stay friends. Or hell, I'm not sure if I'll do something stupid like introduce another love interest.
As for RPM-Vengers, Josei/Batguy has no actual love interest. He just pines over pretty women. I'd like to imagine his character as in the slump that I was in a few years ago where he has waifu on the brain and is reluctant to do anything about that.