I just opened up a private tab and did this (and by the way, going in, I was and am already suspicious that Google is in fact using search results to manipulate public opinion, at least some of the time and in an experimental way).

In the top two rows (ie, 8 images), three are from a reddit post about this very controversy.

The remaining five are images of couples. Of these, three are what look to my eyes to be white couples. One is an image of an ethnically Indian couple in an article about not being able to adopt a white child. The other is a photo of two dudes doing a hand symbol together with a caption "black and white couple gesturing with hands."

All of these images seem very relevant to the phrase "white couple."

So, actually, this is a case where Google Image Search gives back perfectly appropriate results, at least for me as of today.