her calling and saying, "I miss you" or "I'm just bored and want to talk to you"?

Congratulations, you "built an app". I mean I get what you're saying and sort of agree, somewhat depending on his skill level. Like if this was hard for him to build that is cooler than if he was just showing off or something. Because yeah, communication is a solved problem. I once built an app that made a webpage that was sort of a coder/decoder for our messages so my then-girlfriend and I had a "secret language". To me the appeal of that is that it was novel/silly/weird and it was unique to us. Which I guess is sorta like this app.. but I dunno, this one also seems a little prone to abuse and one dimensional.