I heard a saying of Imam Ali (as) which states whatever is meant for us will never miss us. Does this also apply to our future spouses if they are meant for us? And does Allah (swt) decide spouses for us but we also play a role or is it 100% freewill when it comes to marriage?

1- Yes this includes a spouse as well.

2- Allah has decided on the system and what variables have an impact in this system, and one of the variables is one’s role/effort. So we definitely play a role in what Allah has willed for us and determined for us.