Robert is definitely boring, at least to the majority of players. He is the average guy. To be honest, he isn't a bad guy or anything. He isn't a sociopath like Axel or Seymour. He isn't some kinda saint by any means. By and large, he is a typical guy. He is not remarkable in any category, be it career, charisma, intelligence, confidence, maturity, or prowess in bed. He can be quite petty and get butthurt if you reject him early on, but he seems to take it well if you reject him after the fight with Ian. Essentially, he is the embodiment of a somewhat sociable dude who somehow scores with a 10/10 Lena. He is infatuated and clingy. He is always afraid of losing her and feels insecure, but can overcome it somewhat if Lena strokes his ego for him. Lena is the one who holds all the cards in this relationship. I think the character is pretty well realized as he was intended. It's just that this type of character is not something many people find exciting.
He is basically sitting between Stan and Mike in terms of the power dynamics with Lena. So he does have a niche. That said, it's a very flimsy niche. Stan can fill the needy, infatuated, loser role. I was thinking one way to go with Robert might be to make it about femdom. I hate femdom so I wouldn't play that route, but at least he would have an established target audience. Like it doesn't have to be femdom straight away, but as the route progresses we already see Lena holding all the power in this relationship. I think femdom could be introduced sometime after the fight with Ian or something and build it up from there. Instead of the dirty talk option being about being his whore and building up his ego, it could be about negging him.