This is kind of a depressing twist, but probably one that many people encounter at least once in their life.
So in the one corner we have Tai, heavily embarrassed by her admission of feelings to Dora. Possibly so embarrassed she may even avoid Dora for the forseeable future, and if not will most likely avoid talking about said admission.
And in the other corner we have Dora, who while stunned and probably flattered by Tai's admission of feelings, appears to have self-esteem issues so strong they'll make up any excuse to get her to believe that Tai won't (or can't) follow up on her admission. Which means Dora probably won't follow up on it either.
End result: both miss out on their chance to at least try out a relationship with each other. Unless one of them breaks the stalemate and actually goes and talks to the other one. Which, this comic being how it is, could actually happen, but it'll be a while.
You pretty much summed it up how I see it as well. Dora's self esteem has never been particularly noteworthy. She retrospectively sabotaged her OWN relationship with her own insecurities, and most likely still has lingering issues (ones that those memories will more than willingly replay for) that leaves her emotionally blind ("she's so blinded by her own emotional past, that she can't see what's going in her present" is the closest meaning I can think of).
Tai's always been interested in maintaining a stable, monogamous relationship, but so far has never managed to achieve one, not even for a short length of time. One-night-standing and polyamorous romps are no ways to learn about relationships (they're fun and all, but sex is meaningless if your pursuit is about love).
Whether either of them like it or not, no matter how uncomfortable one or the other is, or how they think the other one is, they're going to have to talk it over. Sober if possible.