I mean, Renarin has a crush on Rlain, so maybe Kaladin is too human for him lol.
Actually speaking, I think Renarin (and most members of Bridge Four) idolises Kaladin, so Renarin sees Kaladin more like a hero that he looks up to than a possible love interest. Moreover, there is this scene in OB where Kaladin think Drehy is feminine for courting a man, which may have hurt Renarin since people had already tried to insult him saying he's feminine.