I don't know if a lot of people out there find themselves re-watching the episodes but perhaps the idea will spurn some interest into doing so because as I sat down and rewatched Extinction, I noticed for the first time.
In the opening scene, Trip gives T'Pol the Geogia peaches and she says that it won't make up for having missed two previous sessions... If you watch her eyes as she takes a bite into the peach, she actually begins to smile briefly. It's not a huge movement, but with T'Pol (and Jolene) even the tiniest perturbations are exceptional. When she then chides him for missing two sessions, you can see the 'you were late for our date' look in her face too

I also rewatched Twilight and it was very difficult because it seemed like the writing was trying to force T'Pol and Archer together but I noticed for the first time while watching this episode that either Jolene didn't wanna act it that way or they were directing her to look evasive and discomforted by the mention of emotional attachement to Archer. While it is obvious that the undertone they were shooting for is that T'Pol's cover story was that she was just paying back the favor that Archer owed her for saving her life while she secretly has feelings for him and that being the real reason she's taken so much time to take care of him. But if you watch her facial expressions when she is confronted by having to tell Archer about what happened and having to tell Phlox what happened, it is nothing like that which she shows in the real universe episodes when she's forced to confront her feelings for Trip. Her expression in Twilight is one of frustration and irritation, not anxiety and embarassment at the inability to confront the emotions. Although, the "our relationship has evolved over the years..." "How far has it evolved?" *deadpan* is really out of nowhere when compared to this. Why would T'Pol - should she have them - be able to confront her feelings for Archer straight-faced yet be so immature as to be unable to confront them with Phlox, someone who has been a closer and more trusted confidant than anyone else?
I think that line's a throw-away. I also think that the scenes where she and Trip have some contention and confrontation is pretty much solid lead-up to there being some repression and resentment as a result of her spending a lot of time with Archer and no time with him. IMO, the tension and silent yearning is there in their interactions.