Alice is the best at her profession in the world, and Bob knows this. He wants her to join him and help in his potentially evil goals, but she refuses because she's happy with her friends
and family (especially spouses), possibly even having quit
from Bob's team in order to be near them.
How does Bob get her to join? He kills or kidnaps these people to remove all her links to mundane life. Usually he's smart enough to frame one of his enemies or at least make it seem like an accident, that way he can channel Alice's rage and despair towards his cause.
You can expect fireworks to come out once the secret is revealed.
Sometimes, Bob does this because the loved ones were "limiting
potential", and he considers this a favor!