So spitball math. First, I'm surely this is a grossly overexaggerated number but lets roll with it.
50k texts, that's 25k from each unless its a chronically lopsided conversation. (which is very possible).
5 months, 5k per month, that's averaging ~166 per day, every day, no breaks. Or 10 per hour, or one every 6 minutes for every waking hour of every day for 5 months.
Or, if you assume its a fast back-and-forth consersation, lets say 45 seconds to type, send and have received each message. Doing 166 of those would require constant work at that rate for > 2 hrs total every single day.
I'm pretty sure this must be a made up number.