This was going to be a quick one that I decided on, like, yesterday. lol whoops.
The Way We Never Were: a Boomer/Tyrol minifesto Boomer/Tyrol, on the outer edge of the main cast, constitute the major star-crossed romance of the first season. So already, I liked it because it showed that the narrative was using romance correctly - as something to give us an easy emotional way into the story, and in order to give some added poignancy to Boomer's identity crisis as she's trying to avoid knowing that she's a Cylon, but without overtaking the plot. For me, it worked exactly as it should. I liked Tyrol* and loved Boomer, so I wanted them to be happy, but they weren't really make-or-break for me. Starcrossed, cute, but not that important.
One key part of Boomer/Tyrol, even back in Water, is Sharon's instinctual ability to use the affection she and Tyrol have for each other to protect her own survival. What are we going to do? It's really important that you believe me. And so on, and so on. Boomer's certainly not calculating her behavior, she's hardly aware of what's going on, but she absolutely knows how to keep Tyrol on her side. It's to a much smaller degree, and a whole lot less morally appalling, but it's the exact same tool that the Sharon down on Caprica is using on Helo, and the same game Sweet Eight will try to pull on Felix in the raptor during Face of the Enemy. That's not why they're starcrossed, certainly, but it's a key aspect of the whole production line.
Oddly enough, the whole business with Hannibal Valerii throughout S2 is the time when Sharon and Tyrol are at their least messed-up since the miniseries. She gives him some reassurance that Boomer wasn't lying to him or using him, and that Boomer's feelings for him were real. I don't doubt that Athena was motivated at least a little bit by those soft-power survival instincts, but I also don't doubt that she was telling him the truth.
Tyrol's crisis in late S2.5, then, didn't necessarily make a whole lot of sense - he'd worked things out as best he was able to about Boomer, and so dragging her into it felt at the time like a bit of a reach. But in retrospect, it's brilliant. I'm familiar with the infamous dartboard anecdote re: the Final Five, but I think that's a bit of an exaggeration - the show was careful to lay the groundwork for several of the long-running characters to have been Cylons, one of whom was Tyrol.** LDYB suggests that Tyrol knew, somewhere in his subconscious, that things didn't quite add up, for Boomer and for himself.
The show doesn't do anything so simple as to claim that Boomer/Tyrol was all fate/programming, though. How much the Final Five made their own choices with the remnants of their personalities that were left over after the memory wipe is, IMO, one of the most interesting threads throughout 4.5. This parallels Boomer's own struggle with her own agency and sense of reality.
Anyway, the thing that makes Tyrol/Sharon such a very, very wrong ship is the nature of the Final Five business - not just that they are Cylons, but that they are Cylons who made the other Cylons. All the sweetness of S1 becomes seriously (and therefore FABULOUSLY) disturbing in retrospect. Sure, maybe it was just a sweet star-crossed romance, or maybe, it was an exercise in narcissistic, pseudo-incestuous fascination with his own creation. Tyrol's obsession with Boomer toward the end of the series emphasizes the depths of his assholery bleakness of his spiral.
Boomer, for her part, clings throughout to the memory of what she wants to have had with Tyrol throughout the series. (This is where I stop even pretending to be objective because I love her forever okay.) It is the ground on which she meets Caprica Six, to try to make a difference. Her disappointment in New Caprica, at least as much as her disillusionment with love, spurs her to try so hard to shed her humanity. And yet, as we find out at the end, she has been retreating to a dream of the future she likes to pretend she'd have had with Tyrol all this time. Boomer's picture of Tyrol, ultimately, is so idealized as to hardly even resemble the character we know on Galactica at this point in the timeline.
The last word on Boomer/Tyrol becomes a deeply painful reflection of the whole "personality creation" project surrounding the Cylons. That history never happened; that future never would have happened. The relationship, as real as it was, was never truly like the one she imagines in her late-season projections. As Cavil, the humans, and the Final Five have done to her, so she turns around and does to her idea of Tyrol - she makes him what he needs him to be.
*lol. **(I think this is very much true of the Tighs as well, whose alcoholism stops looking like self-sabotage and starts looking like self-medication against all the cognitive dissonance Cavil's memory wipe would've, forgive me, installed.)