at the end/ in the end

Betsy asked me to remind her to buy milk. ... the end, we both forgot.

We didn't know what to do. However, the problem resolved itself ... the end.

The plot gets even more tangled ... the end of the third episode.

I should pay these bills ... the end of the month.

Students must take an exam ... the end of the course.

Did he agree to cooperate ... the end?

... the end, after a hot dispute, Colin gave in.

I was very tired ... the end of the week because I'd been working really hard.

The author gives a summary ... the end of each chapter.

— Who of you two was right ... the end?

— Alan was.