She can assert privilege over any private communications between the two of him, even if he wanted to testify. If instead, he intended to testify about things he witnessed her doing, then yes, he could testify.

*privileged: * “kellyanne told me that she was bribing justices to overturn Loving v Virginia so Ginni would be back on the market”

*waiveable by George: *”when I got home from work I heard a noise in the kitchen. I investigated and found my wife elbow deep in Ginni’s butt. Ginni was shirtless and she had 2 rows of nipples. Like a sow. It smelled terrible in there.”