Manka are you going to constantly require that we try to keep Cat and the others happy or have it maxed out and stay that way at some point as it seems that as we get more girls then it will be more and more difficult to have time to get the items that make them happy especially when it doesn't tell us what items are needed all the time.
Hi! Relations aren't dropped by themselves, they get lower if Cat is starving or by the scenario in some cases. When you have good relations with the girl, you may ask her to help with hunting or foraging, so more girls make the basic routine easier. But we can say that there is some balancing needed and it's planned!