Spoilers for 02X12
I'm not sure if Chris Chibnall had this back story in mind when he wrote Cyberwomen but it really explains a lot about that episode: Why Jack took Ianto's betrayal so personally, why Ianto had to hide Lisa from Jack.
What I found the most interesting was that Myfanwy was responsible for the first time Jack and Ianto really connected (the rolling scene). I think that may be the reason Jack used Myfanwy to kill Lisa, to really punish Ianto for his betrayal.
As for the rolling scene, I thought it really showed Ianto conflicting emotions; he's attracted to Jack (they were laughing and it looked like they were going to kiss) but he still loves Lisa (he pulls himself away). This could always be considered as canon evidence that Ianto didn't start sleeping with Jack until after Lisa died.
I also like how they handled Ianto's 'agenda'. Ianto's face when he found out he got the job really spoke for itself; he knows he'll have to lie to Jack, but he already hates it. Ianto seems like the type of person who would do anything for someone he cares about, I just can't imagine him being cold-hearted about it.
Jack wants nothing to do with Torchwood One, which could explain why Ianto felt he couldn't tell him about Lisa.
So what does everyone else think.