As to Miss Anne Vane, no one, including Halsband, bothers to explain why if she had no inner or outer qualities, and wasn't rich or titled, men kept being attracted to her.

This was my reaction! "Um, they must have seen something in her..."

He composed a letter and asked his brother-in -law Bussy Mansel to take it to her, telling him that it merely recommended a midwife. Actually it castigated her for the ill service she had done him with the Prince

I must admit I laughed. Hervey, here I thought Voltaire acted like an emo teenager... omg, that whole thing is just hilariously soap opera emo. (though in a way that sounds utterly horrible for Vane herself, of course)

Although they realized it was very indiscreet their 'mutual inclination to meet forced them to this dangerous course

Me: Wow! I guess... they must have been really attracted to each other --
Selena: It's worth bearing in mind, though, that Halsband's sole source for these subsequent shenanigans (i.e. all that happened after the initial fallout between Hervey and the Prince over Miss Vane, for which he quotes letters and satiric poems by all the other London wits) is Hervey himself in his trashy tell all memoirs.

Voltaire: It's not like there's anything wrong with fabricating stories about your ex when you've had a bad breakup!