Peanut, you can thank me later....
Now that makes total sense as I get asked that every night!

But seriously. It isn't that she doesn't want you to ride the bike, it's just that you have shown her (in a roundabout way) that you are safer on tar and she wishes not to get one of those dreaded phone calls. Yes, it is completely illogical as you can get hurt anywhere, but in her mind the tar is the safest option.
That said, if I had to tell the other one to only ride tar he would tell me to get stuffed. I also know his riding capabilities and I worry more about his
super kak driving skills than his riding skills... on the latter, he knows what he is doing and I also know the risk associated with it, but I wouldn't dream of stopping him doing it.
If I get that phone call one day I do hope it was on the bike and swift. It won't make things easier, but at least he went out doing something he completely and truly loved.