But Jac also "has something" on David, i.e. he knew perfectly well that David had taken his wallet and phone after Jac was knocked unconscious (by David, but I think not intentionally). The idea was for it to look like Jac had been mugged by some stranger.
But when Jac recovered consciousness, he made it perfectly clear to David that he knew David was the guilty party. David had to buy him a new phone. (I don't know if he also made recompense for the contents of the wallet). It was a right old smonach / llanastr for David really (just like he's in now actually! For a boring finance-type person, he seems to lead a dangerous life ....).
I think Jac will definitely force the issue, and make David come clean with Dani. Whether that will lead to true happiness for him (Jac) and Dani, remains to be seen.
As for David and Rhys, I think that relationship is doomed, somehow.
BTW, I seem to remember that Rhys had confided in Barry about him and David. Barry and Rhys were old friends (before Rhys came into the programme, but it was made clear when they met again, after many years. Think they had played football together). Barry seems to have kept quiet about it though. So one way or another, David's secret is out.