I know Reina is kind of desperate for some progress, but I don't know why I can't shake off the feeling that Hinomaru, rather than dating her, wants to actually marry her. I think that's why he's telling Reina to wait.
@ElBichoRaro yup, I agree.
Just see how he reacted to the "marriage" proposal his master showed him, he wasn't embarrassed by the girl actually being interested but rather by the fact a girl OTHER than Reina actually considered it.
Oh well, that's my take on it.
@Shyning: It came mostly from when he noticed Reina's feelings during that walk on the beach. He said "Maybe not date, oh, but actually, y'know..." and he stated that it wasn't his decision alone. That simple sentence is what made me realize this theory. But at the same time, he's very insecure about being someone that deserves her.
@ElBichoRaro Classic feelings "not sure you deserve the other" (which usually is shared by both, makes things difficult).
But yeah, I didn't think of that time on the beach, looks quite accurate too !