trailer couplers

I get that, that's why we went s l o w, and thru the country, weren't fast enough for a fishtail, went slow enough to keep that from happening, I still say that the ball should not have become uncoupled without broken parts or the lever able to pop up. I acknowledge it wouldn't tow very well at speeds much faster than we were trying to go...
This is the first time we have had to move the tractor with the deck mounted, farther than we were willing to drive it down the road, it's far from an everyday thing or even a once a year thing.....
If anything we're moving the tractor with a bucket on it which (again without the deck) fits this trailer just fine. We knew that it wouldn't tow nice but also knew we had to move slowly, but certainly didn't expect it to come off the ball while still coupled. We get it we weren't going across the county or anything with it.... Everyone here has had to "make do"" with what they had available/ at least once over the years
We knew it might be a problem but certainly wasn't expecting "that" problem /strangely none of the issues we thought could happen, did.