There's a stupid logic in breaking up with your girlfriend just cause you don't want to endanger her. She's still has the connection and villians who do their research will logically still target her even if the hero send her away. Doesnt mean she can't still be used as bait or a weak point.
Motto. It's not like a villain is going to think "hummm, I could kidnap and/or murder this woman, whom the Thing loves, but she is not his wife so I shouldn't bother." If anything, as his wife, she'd be more protected because she'd live in the Baxter Building and she'd be almost always near heroes.