There's nothing in the Vatican II documents that a reasonable person would interpret as either an endorsement of, or injunction against, hand holding. It's simply a non-issue, which is what I wish it would return to being.

This topic isn't worth space on this website and it isn't worth worrying about during Mass. if people want to hold hands, they'll hold hands. If you don't want to (as I don't), keep your hands to yourself and face forward. People get the message without offense. I've never seen it fail.