Feeling like relationships dont exist??

Sorry, I know the title is weird. But lately, when I look at texts and things from my friends, I couldn't care less to reply. They ask me to hang out (im not a very social person anyways) but now I completely dont care to say yes, even just to be nice. When I look at texts from my friends, I look at their name and try to grasp something tangible from my heart, but there's nothing there. It's not that I don't care about them, I've known them for years, but it just feels like our friendship is...idk. based on nothingness. i dont feel like theyre friends, just people who keep sending me messages and I dont know why. has anyone else ever felt like this what does it mean sob