GW2 repairing its data

This is the second time GW2 is repairing its data (it did so after last update as well) - it's been a long time it crashed for me, I've never forced it to close, so can somebody please tell me why it's now repairing itself?

edit: and the repair process is not responding now?

edit 2: after I've forcibly closed it, it didn't need to fix itself anymore? Can somebody help me understand how this works?

My game just decided to repair it's data also, it's being incredibly slow so it may have crashed? I'm not sure what this is about.

(edit, it did crash..)

I've hit no to the repair? question and the game works just fine. If I hit yes to repair (which happened on my desktop) then it crashed, and I had to download all of GW2 again.

When I hit no to the initial repair prompt, the game launcher never asks again (or at least hasn't since I hit no on my laptop)

Mine had to rebuild files from database the other day for a patch. 2 of my friends had this too. Not sure why.