@kronix Did you not see the developments progress in the past? Do you expect for Yae to notice from one chapter to the next and have them be a couple in a few chapters?
If you look closely there is development, albeit it's very slow but I prefer they have a slow yet progressing and fleshed development rather than rushed... especially since they're childhood friends and both very respectable human beings who care about the other person's well-being rather than do things on impulse that might destroy their relationship. It's very realistic so if you don't like it and want to see fast development, this manga isn't for you.