I may not entirely understand the question, but I do believe white people can fight systematic white supremacy, just as well as men can fight the patriarchy (see: A Man's Guide to Smashing the Patriarchy: https://keralataylor.medium.com/how-to-dismantle-the-patriarchy-a-guide-for-men-3c4287f4f518)

So if both partners in an interracial relationship are committed to fighting white supremacy, I would say absolutely. The problem I've witnessed is that most white people, even white people in interracial relationships, aren't willing to put their own comfort on the line.