Bashful lovers are embarrassed by the physical side of love--embarrassed by their own desire, embarrassed by waking up and having to talk about it. The reaction may seem a tad cloying (and frankly, can be) but at its simplest, it can also be touchingly honest since it tackles the fundamental strangeness of lovemaking, as exemplified in Friends when Ross and Rachel watch a video of them having sex and realize that they aren't exactly porn stars.
Bashfulness can also give rise to funny moments. In Candy Color Paradox, Onoe's bashfulness the morning after--"So embarrassing"--is offset by Kaburagi's hair, which is amusing in its own right.
And bashfulness no doubt attracts some readers/viewers. I start to lose interest when it becomes a plot device. Pete in Love by Chance (above) is bashful, though (slightly) more experienced than Ae. He gets upset when Ae mistakes his bashfulness for lack of interest, but seriously, what is Ae supposed to think?
In contrast, the "look dude, I'm keeping you at arm's length" Can from Love by Chance (both seasons) is inexperienced rather than bashful. He is entirely willing to address Tin's penchant for physical touch in Season 1 (once Tin figures out how to manage Can, he pursues him without hesitation). In Season 2, once the two decide to sleep together, Can cheerfully goes off to buy "protection," leaving a nonplussed Tin by the car. We know Tin isn't as "man of the world" as he is acting because...he straightens his tie (an ongoing behavior tic).Can's inexperience is partly due to literal inexperience and naivety but also due to a wariness of any relationship's potential black-hole. Can knows himself well enough to know that once he makes the leap, he is all-in, forever, without pause or hesitation. I found the link in Season 2 between Can's reluctance and Ae-Pete's separation entirely believable. (The actor playing Pete didn't return, and the writers used the non-return quite intelligently.)
"Why would I want to do something that hurts me the same way it has hurt my friends?" is Can's argument. And Can (like Tin) cannot separate physical affection from mental commitment. In fact, Can's instinctual awareness that Tin also doesn't do anything by halves contributes to his understandable wariness.
Once Can makes the leap, he is entirely happy with physical intimacy and will initiate it.
Generally speaking, Asian BL is quite refreshing because it allows for people to be uncertain and uncomfortable in the bedroom without automatically being labeled "repressed."
Granted, the tropes can be taken too far.