https://ethics.house.gov/publication/code-official-conduct
18. (a) A Member, Delegate, or Resident Commissioner may not engage in a sexual relationship with any employee of the House who works under the supervision of the Member, Delegate, or Resident Commissioner, or who is an employee of a committee on which the Member, Delegate, or Resident Commissioner serves. This paragraph does not apply with respect to any relationship between two people who are married to each other
Yes it is a major ethical breach but she will get off Scott Free because she is a bi-sexual and (most importantly) a Democrat.
Oh, and because the Democrats are in the majority of the House at the moment.
All pretense of fairness and following the rules is long gone.