As many have mentioned, could be corrupted game files; but only you know if you been monkeying....
Its a guess at best.
Could be your comp needs a cleaning (once a year), getting hot from dust clogs or slow fan. Only you know.
If like me, game worked flawlessly, but started crashing, and i havent changed any files; but my comp was overheating from a fan failure.
Fixed that and the game was still crashing to my surprise.
As i considered a re-install, I noticed my HD was also getting pretty full so cleaned it up some, moved some files elsewhere and the game is great again. No re-install. Seems you need a good 100GB of clean space, or i do, with the other stuff i have running in the bg.
Consider maybe your HD has a bunch of files recently added (torrents maybe?) and maybe used up too much space. Move them elsewhere to another HD. Its a very resource demanding game.
Find your Bannerlord.exe file, r-click, select Properties, and then Compatibility tab, and check the 'Run as Admin' option and 'Apply'.
Update: Game started crashing again after i replaced my fans. Case is cold!
But, seems i got a bit adventurous on the video and performance settings after i swapped them around the first time. And again when i replaced them. I knew my game played flawlessly at one point so wasnt in the game install itself. It had to be something else. So i uninstalled and re-installed and stripped everything out, residual folders and files etc. Still had a problem so went over the video and performance settings and remembered that water and shadow settings can tend to need to be turned way down. Tried that and was an improvement.
Suggest you set your overall settings to medium or low and your crashes should stop. If so, then ypu can slowly up them in areas. Water, shadows and some lighting effects are probably best left low altogether. Its not a water game so you wont miss it.
My card is 3gig of ddr3 i think so i was playing well at high with just a few things turned down. So it depends what yur using.