Captain Britain is a mutant now. The Queen of England is concerned because their representative and Champion in Otherworld now has ties to Krakoa. Formalizing a relationship with Betsy and her current team just makes sense. It's helping to make sure that Betsy will prioritize an emergency in Otherworld over something like say Xavier's assassination placing the island on lockdown.
Meggan's a mother now, and her husband was just brainwashed and turned into a servant for one of the most powerful sorceresses in history. That's all very concerning, and if she isn't confident enough then she's more vulnerable to losing control of her empathic powers and letting the hate mobs get to her. So right now her priority is protecting her kid.