Based on a October 1, 2017 report by Mikey Smith of the (UK) Mirror, October 1, 2017.
Details of the possible frigate affair go back to 2014 when Sarah West (above), the RN's first female warship captain, was removed from her command of the frigate HMS Portland, with the RN just citing an "internal matter". She was reassigned to another post.
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The submarine affair is current and more serious because the Vanguard class sub involved is an SSBN specifically designed to launch the nuclear weapons on board.
Senior naval officers have been sent to the SSBN, deployed in international waters, to deal with claims there was an “inappropriate relationship” between a male and female officer. The female officer is apparently innocent of wrongdoing. RN woman were banned from serving on submarines until the rules changed in 2011.
COMMENT
My limited knowledge is that the Royal Australian Navy works on a less formal "don't ask, don't tell" basis, with far less publicity.
Pete