Yes, witchmountain, which takes me back to where I came in, asking whether anyone else feels that they're re-cycling old plot lines at the moment. Seeing and questioning plot-lines or devices makes you step out of your belief in the characters and their behaviour.
For that reason I've never forgoven them for killing Nigel, because of the way it was publicised in advance and clearly planned as 'we've got to do something big to get people's attention'. I didn't 'accept' his death until the characters reacted to it and there was no going back.
With Lily, the 'older man' and 'discovering the downside of being in charge of every aspect of your life' is entirely in character and long-signalled. I just find the 'relationship with lecturer' bit odd, because it seems so out of time, something people really did do back in Debbie's day but are all much more aware of the taboos around now, especially in a sixth form college.
The Pip job-chucking decision is debatable in character terms (I can see that the idea of being away from home, or any home, while moving around establishing the high-flying career might have hit Pip hard) but what irked me was the clear need to keep her in Ambridge to give the Fairbrethren something to do. Interacting with people you're not that close to is not a reason why people make decisions about jobs.
I've always thought that Rex is hanging around (character and plot) to be there for Pip, at some point in the distant future. If he got something going with Lily, maybe in five years when she's more mature, that will be the moment that Pip suddenly realises she wants him.