Ending explained (spoilers)

The plot was that they had to make amends or they will keep repeating wedesday. Whatever they did on wednesday had zero consequence. They'd just repeat the day again with a clean slate
However on the "Wednesday" that Kyle and Sonia were making amends, Weeks was busy shooting 2 cops (as shown on the news as Kyle entered the house to talk to his sister)
They all get pushed past the time loop to the next day which is Thursday.
Weeks as usual goes crazy (thinking it's still wednesday) and continues terrorizing and killing yet more people until he finds out it's Thursday which leads to his eventual suicide.
.....However after killing himself he wakes up again on Thursday. The problem for Weeks is that he doesn't start Thursday with a clean slate because on the Wednesday before the loop lept forward to Thursday he'd shot 2 cops (and god knows what else)

So he's screwed.He's either Doomed to repeat Thursday with all the consequences of the day before OR even if he did make amends with his dad to try and make the loop stop (which would be pretty tough with the cops after him)he still has to face the music and "make amends" for the 2 cops he shot!