No, thats not how it works. 40 point of gain or loss are just one time things, usually when something is done the very first time.
Its a stat grind game so to point kinda is to make it a slow gain
Books are a one-time boost, figure out which flirt action gives the most point, you can do flirt option at every single time of the day so keep grinding (learn where they are each time of the day). Give gifts when you have the money, keep studying with them, Date, do sex options the same way flirting does.. figure out what they like. The more often you do something, especially if they liked it the first place, the more they will like it
Thats basically it. A mistake takes off very little points... I always go for obedient route and man its a struggle to keep Love score below obedience
So you must be doing something spectaluarly contraproductive if you wanna do Love route.
Joke asaide, its a grind game so it will take a while.