I am not sure about the married and out rule.
I do know of two cases where an officer married an OR. In one case he was an ex-AEOp, maybe even ex-airman, so marrying 'below his class' was not an issue. His marriage was discouraged and it was made clear his wife was not welcomed in the Mess. This was 1968. I met him about 2005, he was still serving as RAFR.
The other case, same station, same senior officers, and again discouraged against marriage. They made his life so difficult, Vulcan captain, that he was forced out. He then got his majority in the TA. Still married 50 years on.
1975 very definitely married WRAF quite common (but not pregnant).