It's a comedy whose premise doesn't bear close scrutiny or it becomes an existential horror flick.
Why would the universe care that some random dude is a douchebag who needs to end up in a relationship with a particular character? In some branches of a multiverse, a version of him does, but making him experience all the branches to be able to ratchet his way to a very arbitrary goal by exploiting memory seems like the behaviour of a cruel godlike entity, similar to the Ancient Greek ones.
Isn't this sort of behavioural reprogramming the sort of thing the Chinese Communist Party used to do?
I think you are really overanalyzing it. Valid points but I think you are taking it to heart a little