This doesn't seem to be the case in Canada. My sister is married to an Indian fellow. My girlfriend was born in Xiamen. During high school a huge percentage of relationships were mixed race. Canada is a melting pot and it seems to work well.
One anecdote
> My girlfriend
Another anecdote
> During high school a huge percentage
Now we're talking percentages, which is better. But you'd still need something better than your recollections (and probably something more specific than "huge").
Obviously, there are plenty of mixed-race relationships, and plenty of them are happy. But there is research that seems to indicate that there is something to what the parent comment was suggesting: http://en.wikipedia.org/wiki/Interpersonal_attraction#Simila...
Same article claims that in the US in 2010 the rate was 8.4%.