I must clarify that this observation is with a third party not me (not bias)
Wouldn’t exactly call that unbiased, (their perception of events and your perception of their perception can lead to some off base stuff lol), but let’s do it anyway
She could simply not be interested in him.
But if we were to assume that she liked the guy, but only acted in a flirty way with one of them. Theres a few reasons that could be in my mind.
What your definition of prude is also plays a role.
- She feels more pressure to keep up a facade of being more virtuous than she really is.
This might be because she simply likes the guy more, and doesn’t wanna do anything that would put him off of her, obliterating her future wife status. In this case being sexual.
The guy may not come off in a very sexual way, or has expressed views that indirectly say he disapproves of girls who are “slutty”, that sleep around/have passed the threshold of an acceptable partner count.
Or maybe he hasn’t expressed anything like that, but hasn’t not expressed that he likes when women are sexual, i.e by being a sexual person himself so she plays it safe. He’s not presenting himself in the right way.
- There could also be contextual factors that play a role. Who’s watching, where they are, how she’s feeling that day, whether or not shes ovulating.
- She simply feels more apprehensive around the guy, kinda goes back to number 1. I’ve found that some girls aren’t all that comfortable flirting with the guys that they
really like, they can be more passive and shy, but can do it more actively with guys they feel like they hold more sway over. It’s kind of a weird thing to experience.
There’s really no saying without more context. But generally its because the guy hasn’t made her feel allowed to. It starts with the guy.