The drama in a coworker's private life is leaking into your relationship with them: and it's going to start complicating things today, especially if this coworker has power over you. This could be a tricky situation to maneuver around, but you can do it. You've got the charm, you've got the tact, and you've got the good reputation required to get your stuff done without having to get them involved. Let them do their own thing. Decide not to count on them.