Yeah, they were having a torrid affair in season 7.
Here is a VERY SPOILERY article on Foxtel about Allie's character, in which Kate Jenkinson explains why she became Top Dog. The pertinent bit:
Yes to most of your points, @zibnchy, especially about Lou and Reb, and Linda Miles. I would add that this season has brought back into focus how much of a loser Vera is. Remember in the first few seasons what an intentionally pathetic character she was? Also: I wonder what Marie is up to with Sheila. Very intriguing.
I tweeted after I watched the finale that they have set everything up nicely for the final season, and that I can't believe we have to wait so long to see it (apparently it will air in April 2021). A person I follow on Twitter who works on the show tweeted me back and said, 'It'll be worth it' with a winky-face emoji.