I never has issues with Europe and I've traveled so many times from and to Europe lol. And yes I am from a visa exempt country. Europe isn't strict at all, when my partner or family visits me it always surprises them how easy the boarder is here and the lack of questions they ask you, they don't even care much about me when I board a plane to the US. The issue is the US boarder, never once had I a bad or troubled experience traveling around the world (boarder wise). Except a couple of times at the USA boarder, no matter if I was just transferring through the US, or going home to Europe from the US, or even going to Canada from the US or the other way around. I have friends being denied without a good reason (visa exempt) and also almost being denied myself when I went from the US (was just transferring) to Canada.
It probably will be alright, I highly doubt they will deny him. But yea there is no guarantee. They have no reason to be scared, but that doesn't mean they shouldn't be aware of issues that people from visa exempt countries have with the USA boarder. It isn't that uncommon that people get denied from a visa exempt country without any good reason, just having bad luck with the wrong officer that is in a bad mood or abusing their power.
Also her husband isn't a US citizen but South Korean.
But only time can tell~
There is almost no way he would be denied in Canada with his copr, so yes IF something would go wrong it would be there, but it probably will be alright so don't stress about it too much, they usually often delay more than deny visa exempt people (unless you clearly wanna overstay in the US)! Just be aware that they can be pretty nitpicking or mean sometimes with their questions IF you have a cranky person at the boarder, but that mostly would only delay him. Lucky there are enough nice or not cranky officers too haha! Just have a return ticket upfront and the chance is really small something would happen.
