FYI: You can still improve relationships after the big date in Chapter 12

[Time Traveler]

Without too many spoilers, you do not need to worry about doing all of the side missions before Chapter 12. If there is a particular member that you want to take on a special date later in the game (beginning of Chapter 12), then you might want to focus on side quests that improve their relationship. Then you can go back and solve all of the other side quests to max out the other friendships without getting the "wrong" date. Hope this helps!

[Scarlet Crusade]

Unless you’re concerned about the side content making sense in context, in which case you should do it all when it’s first available. As long as you choose the correct dialogue choices for the one you want and the wrong dialogue choices for the ones you don’t want, you’ll get the date that you want. Using all of Cloud + <character you want to date> synergy abilities while avoiding all other Cloud synergy abilities (except Cait Sith) will also help. You can use the ones with Barret + Aerith, Yuffie + Nanaki, etc., just don’t do the ones with Cloud in them for the ones you don’t want to date.

[Time Traveler]

Originally posted by Scarlet Crusade:

Unless you’re concerned about the side content making sense in context, in which case you should do it all when it’s first available. As long as you choose the correct dialogue choices for the one you want and the wrong dialogue choices for the ones you don’t want, you’ll get the date that you want. Using all of Cloud + <character you want to date> synergy abilities while avoiding all other Cloud synergy abilities (except Cait Sith) will also help. You can use the ones with Barret + Aerith, Yuffie + Nanaki, etc., just don’t do the ones with Cloud in them for the ones you don’t want to date.

That's good advice. The only issue with this is that you have to be a jerk to everyone else through the story line (or at least a few times to ensure they "like" you less than your date.) I'd rather enjoy the discussions with each of them and then come back and finish the side quests later rather than filling my cut scenes with arguments.

[Scarlet Crusade]

My favorite one was when Aerith was giving her inspirational speech at Cosmo Canyon, gets choked up, Cloud interjects with THAT’S ENOUGH!!, everyone stares at him awkwardly, and Aerith goes on as if nothing happened.

I’m gonna play NG+ anyway, so I’ll get the positive interactions that I missed then, I guess is how I’m looking at it. And fair’s fair, I’ll get the negative interactions that I missed too.