The girl from the rich family writes to the guy who she has now developed feelings for:
あなたと一緒に過ごせる日々を私が可能な限り応えたいと思えるようになりました。
I've seen 応えたい with words like 期待、要求 or 想い, but with 日々? Does she implicitly mean "the happiness I have felt during the days I have spent with you"? And that she wants to give the same happiness to him? Or is it more along the lines of "I came to think that I want to make the time we spend together a happy one"?