white liberalism is in denial. it was warned this would happen, both by the left and the right, and now that it is happening, it can't accept the consequences of it's actions over the last several decades.

they were supposed to assimilate. 

they were supposed to be just like us.

the liberals didn't listen - just like they didn't listen when the left and right warned them about hitler. just give the migrants a bit more space. they'll eventually want to fit in.

...and now we have a huge problem and we're going to have to address it and it may require a lot of violence.