Never gonna happen. Marvel brands its own stars, it's not going to want some other property's branding or fanbase expectations to be part of their design.
Further, it would be a bad career move for both Kit and Joe to get typecast as a couple. This isn't the 1930s or 40s anymore in the old studio system where people did this over and over again. J-Law and Cooper did several movies together a decade ago, yes, but at least two were huge flops and they weren't always romantically paired. Even Tom Hanks and Julia Roberts don't do them together anymore.