Checking Answers

Here's my take:
Sensei lost his teaching job after he created a scandal by
becoming involved with Kanon. Now, judging by his work
uniform, he's been reduced to the rank of a store cashier,
or a shelf stocker, or a similarly lowly position.

Kanon & Sensei love each other, but their relationship is inherently
unstable, because Sensei apparently suffers from low self-esteem,
which has been exacerbated by his fall from grace, and by the age
difference between him and Kanon. He's afraid she will eventually
run off with a younger, more successful guy. That's why he panics
when he comes home and finds her missing.

His anxiety is unwarranted, because Kanon is fully committed
to Sensei, and has no intention of leaving him. However, she's
immature (as indicated by her slender, waif-like appearance),
and not particularly bright. Kanon's a sweet, good-natured kid,
but she's not an ideal wife for an older, college-educated man.

For all his fear of being abandoned, Sensei is the
one who's more likely to give up on the marriage.

In spite of all that, I wish them well.

Sensei is too insecure, Kanon is too immature,
and the age difference is simply too great.