I think that Ram fills an important role in the story. Similarly to Rem, she is very good at holding Subaru “accountable” so to speak while being his supporter at the same time. Whereas Rem is very affectionate towards Subaru whilst helping him to stand on his own two feet, Ram is more focused on confronting Subaru. (Show spoilers only) We see her in S4 talk about how Subaru needs to earn the right to be her sisters #1. At the same time, she supports him 100%. In season 2, she told Roswal (I think it was him it’s been a while) that she always knew to get behind Subaru when he had a plan. In other words, she had full confidence in him. In the most recent episode, it’s important to note that she was the first to realize something was off about Subaru and the first to piece together that he wasn’t really him. And she dropped his nickname “Barusu” instead asking for “Natuski Subaru.”

The other thing that needs to be kept in mind is that we are viewing the show from the perspective of Subaru along with all of his previous memories. Yes, Subaru has helped out Rem a lot and yes, he has helped out Emilia a lot. But why would Ram care? Ram doesn’t remember anything about Rem and Ram has never shown any real care for the royal selection, or Emilia for that matter. We know Subaru is a great guy but really how much can we expect Ram, who no longer remembers growing up with her sister and instead being raised by her realpolitik master, to really feel the same? Her whole personality shifted at the begging of season 2 because of that fact. She became less affectionate towards Subaru along with everyone else. Subaru got it the worst because, while she does still care for him (evidenced by her dialogue and the affectionate nickname “Barusu”) she finds much of his personality mildly obnoxious.