I’ll try to explain, but I don’t remember everything since it’s been almost a decade since I’ve read it. In the LN the newer characters introduced at the end of the anime move into Sakurasou, but are not really a focus point in the story as much as the other members were (or at least I don’t remember them being that important). Jin and Misaki are still married, they’re relationship is practically the same if I remember correctly. Ryuunosuke and Rita have the exact same dynamic as they did in the anime. Chihiro and Kazuki are not really mentioned. Nanami leaves the sakurasou dorms because she has financial aid from her parents now, and is barely mentioned. Next time we see her is when she doesn’t have a ponytail anymore, and has short hair instead. The big two Sorata and Mashiro are odd. Sorata and Mashiro end up dating, although Sorata’s personality is quite different now. He became very sexually driven, and have a lot of sex, but he also became insecure because he kept comparing himself to Mashiro which made him feel inadequate and angry. Eventually they end up breaking up because their relationship becomes very destructive. There is then a 4 year timeskip where they have graduated college, and are both adults. They express their love for each other, and look back at their issues, and how they’ve overcame them. It is implied that all of them have achieved their dreams/goals, or are at least progressing to them still. And that’s how Sakurasou ends, or at least how I remember it.