I was watching an episode of Firefly the other night, and it got me thinking about what the dynamics would have been for Trip, T'Pol, and Archer if we'd gotten a realistic season five of Enterprise. In the episode of Firefly ("War Stories"), a character named Wash is upset that his wife Zoe, second-in-command of their ship, is a little too close to the captain. While they'd never been romantically involved, they had gone through a war and a lot of other dangerous missions together, were extremely close friends, and he felt like Zoe always unquestioningly agreed with the captain about everything. Wash says at one point that there was "one too many husband in this marriage."
That got me thinking about TT&A, and I could see a lot of parallels between the two groups.
Trip and Archer did have a history of close friendship, but by the third season, I think Trip was closer to Malcolm than to Archer. Archer seemed closer to T'Pol, to me. As far back as season two, Archer seemed to confide more in T'Pol than in Trip, and he seemed to seek her out and listen to her advice a lot more, too.
Throughout the series Archer and T'Pol went on several adventures that Trip really wasn't a part of. I know, the same could be said of Trip and Archer, but it seems to me like the adventures that Archer and T'Pol shared included more personal elements. In particular I'm thinking about all that went down in "The Seventh" and in the Forge during the Vulcan Trilogy. For example, Archer, not Trip, was there when she lost her mother.
Finally, as first officer, T'Pol outranks Trip and might have to side with the captain against Trip sometimes or order him to do something he doesn't want to do.
The question I'm throwing out there is, do you think Trip might be a little jealous of Archer's relationship with T'Pol? Or, do you think the bond would preclude that sort of thing since Trip would be able to sense that T'Pol's friendship with Archer didn't diminish how she felt for him? I'd like to think that the three of them could work out any issues like this, eventually, but it seems realistic to me that there might be some tension for a while as Trip and T'Pol learn to be a couple and Archer learns how to deal with that.