Please note that sensei silently accepted the position of potential future wife.
The only things she ever went on to refuse and deny are things against the rules/laws,
other than that she really aint putting up much of a resistance and also made it rather plain to see who she's interested in.
Been all too obvious for some time that all of them are interested in him, not exactly a lack of signs here.
Personally I kinda liked the detail of sensei buying lots of manga about forbidden love between female teacher and male student, while she bought those childcare books.
She also likened her situations with nariyuki to those of the couple in those manga earlier with female teacher heart throbbing for the male student and all, and even called the manga realistic.
(Amazed that some people still didn't realize though, sensei really aint that subtle to be honest, just strongly trying to avoid breaking any laws/rules.)