Wholesome love, wholesome friendship... it feels like this manga is breaking some unwritten manga laws being this happy this early. Some moments I wonder if it's "legal" for a story to be this wholesome and happy. But I'm well aware the background conflict between their schools is going to be a major obstacle to their relationship. The teachers are bad news in particular. We also barely know anything from Kaoruko's family so that can be a possible source of obstacles too. Just let me enjoy how they're building up Rintarou and Kaoruko's relationship for now so it can better face the trials of these future troubles later.
Subaru's guardian instincts are kicking in again, but this time as an ally of Kaoruko's love. One day she'll move on from the protector role (especially once she falls in love herself), but for now I welcome her continued desire to protect her best friend.
I'd love it for a 3rd girl to join them from Kikyo, but Subaru's not exactly the type to make friends easily. If someone new's gonna join them, it's probably going to be from Kaoruko's efforts given she's already friendly with a number of other girls there. But I don't expect it to come easy.