It just occurred to me that Lester has actually been faithful to Sarah, since Lizzie. I mean as far as we know he hasn't slept with any other women. I wonder if this is a scenario that comes up in the future where he "breaks" a new woman in front of Sarah, or possibly even for her - like the condescending HR bitch.
See, this is why I think the Hospital is going to be the main frontier in the battle between Lester and Sarah. There are so many combinations that could come in play: Lester,Sarah,Richard, Mary, Otis. You could go any different ways like Sarah trying to snoop on Lester or trying to help him take down his competition or trying to make him take out her competition, all the possibilities invariably leading to Lester's dick deep inside her.As I've said before Sarah tricking Lester to take down Mary the HR ghoul is the most interesting one to me as the idea of finally getting a win might send Sarah overdrive and might want more of that high, forgetting operation no more lester on the way.
Also, If I recollect they also have an entire floor to themself. The mentioning of Lester wanting to talk to odious Otis makes me think he might find a secret room between his and Sarah's room or somewhere in the floor that could be their love shack. They have done it in her place, his place, other spots, so the next step would be to have their own space, just for themself, to build more intimacy and memories.