> This has cost me a relationship. (it was long distance to be fair).

Tbh, (imho, having tried it) in normal circumstances it would be a miracle to make anything really work like that, but at present you're just fighting a losing, nearly irreconcilable battle, unless you're both wholly on the same page about infrequent synchronous communication.

If a relationship relies on immediate responses to async, unpredictable, text-based communication, and what you want is a sane lifestyle, it's going to be a tough situation.

I just tell people that need my attention how to get it. Call me if it's important and/or time sensitive, otherwise I'll just check when I check based on the implied nature of the platform. Instagram is super casual unimportant brainrot usually, Messenger for coordinating plans with older millennials and Gen X family, Whatsapp for younger millennials sometimes, SMS or RCS is slightly more important and I'll get visual but not physical or audible notifications. I make it clear that if it's a group chat, I'll turn notifications off unless I'm specifically tagged, or maybe check in once a week if it's for a specific purpose, but otherwise I hate them. Signal for some things that aren't time sensitive, no notifications, no read receipts on any platform.