Don’t avert your eyes, don’t take of the glasses.
Sadly the glasses didn’t stay on the whole time… *starts to sob*
But still: don’t forget to praise the Goddess of Sequels \o/
I believe that has to do with our evolutionary behavior. Acknowledging bringing new life to his offspring as his paternal responsibility, he decides whether to progress further or not depending on his lover's decision.
In no specific order: Touya-kun essentially has Obaa-san's Approval, he walks Mitsu-chan home as her protector, he especially likes when she's all 'tsundere', and he knows what gets her going w.r.t. sexy happy fun time.
Conclusion: Perfect Boyfriend Candidate (don't let him get away, Mitsu-chan)!