He also 'involved himself inappropriately in a job application process' in which the officer he was in a relationship was applying.
Furthermore, Thames Valley Police say Chief Inspector Julian Collinson discussed a police constable subject to misconduct meeting in potentially prejudicial terms with the chair of that meeting without disclosing a conflict of interests.
He also disclosed confidential information from a local Organised Crime Group meeting to other police officers.
Following a public misconduct hearing, chaired by independent Legally Qualified Chair Mr John Bassett, an officer has been dismissed without notice following a misconduct hearing held at Thames Valley Police Headquarters.
Chief Inspector Julian Collinson was found to have breached the Standards of Professional Behaviour.
Thames Valley Police also confirmed that Julian Collinson had breached Standards of Professional Behaviour or honesty and integrity, confidentiality, duties and responsibilities.
These four breaches amounted to gross misconduct and as such C/Insp Collinson has been dismissed without notice.
Detective Chief Superintendent Colin Paine, Head of Professional Standards for Thames Valley Police, said: "Chief Inspector Collinson showed a severe lack of judgement as a senior officer within Thames Valley Police. Senior officers should lead by example, but in this case C/Insp Collinson failed to do so.
"As such he has been dismissed."
"I hope that people will take comfort in the fact that Thames Valley Police has acted to address wrongdoing, regardless of the rank of the officer involved.
"The standards and expectations of the Code of Ethics are made clear whenever anyone joins the force, and these are reinforced repeatedly throughout their career.
"I hope that this is a timely reminder to all of the need to act with absolute integrity at all times, particularly where personal relationships are involved.
"This case also highlights the importance of being responsible and to respect matters of confidentially with regards to operational policing.
"Lastly, I would say that I am grateful to the officers and staff who rightly challenged and reported the conduct. I hope this case will send out a clear message to all officers and staff that they will be listened to and supported when they challenge or report wrongdoing; regardless of the rank of the person it relates to."