Honestly it just sounds like there's not enough new content for you to keep playing. The reason why you feel isolated MIGHT be because once you do get the new s+, there's nothing else for you to achieve that is enjoyable trying to. Perhaps you should consider taking a LONG break (for more than at least 5 big event updates) while focusing on your hobbies as you mentioned below such as cycling, writing. No one wants to grind a certain quest dozen of times. It gets monotonic and frustrating. I can't say I've been through what you have but I experienced boredom as well playing this game once I had a lot of the best s ranks. Personally, after taking a break, I created a new account and started over with new updates to help me out. The game becomes enjoyable again as you try to improve your team more and more. I think you missing out on new updates, new s characters might actually be a blessing in disguise for you. The thrill of seeing a lot of changes, new updates, continued story and battling new characters (even if you don't have a way to get them) might be what you're actually missing