Battles can change any value in the 1/2 Memory block in the savemap. That's the only way the results of a battle can communicate with other modules. As mentioned, the battle love values are not calculated when determining the few things affection points are used to determine. They go up by 2 every time Cloud heals them (their HP has to go up), down by 2 if Cloud hurts them, up by 4 if Cloud covers them, and down by 4 (maybe 9, it's hard to tell) if they die during the battle. Because they're never considered, Cloud's, Aerith's, Tifa's, Barret's, and Yuffie's scripts are pointless.
This whole battle love points seems ridiculous anyway because a lot of it is out of the player's control.
If you want to control exp it would be easy to hijack any/all of these values. Make Cloud's post-battle script multiply/divide the exp by an amount and tell Tifa's, Barret's, and Cid's scripts to copy Cloud's, but it should only run once. That'd be tricky.