You did it! We figured this one out! It is a truth universally acknowledged (by me for certain) that the Bitchery pretty much knows everything, and really, it's true. Scroll down to see the solution for this HaBO - and many thanks!

This HaBO request comes from A.D. and they’ve been looking for this series for years:
I read these books between 2005 and 2006, as part of a historical romance book club. At the time, I never really took stock of names. Each book in the series follows a different couple and I’ve only read two of them.
The first I remember was of an Englishman who falls for an American noblewoman. The girl is also peculiar because, I think ,she liked to sing and may have wanted to perform in the opera. This was supposedly improper at the time. I wasn’t really a fan of it, but the romance was okay. The singing…not so much. In one instance, I think both of them are on a cliff edge and start singing together!
The second book is the one I really enjoyed, and the one I’m trying to find. The man is half English and half French. I think his mother was French. I don’t remember his name or title. He was a quiet man, though. And one night, a young woman goes to his room. I don’t know if she was a maid, but she was definitely not highly titled. That night, he took her virginity (per the usual) and though inexperienced, they had a connection. The romance felt more subdued and sensual than the noisy passion in the first book. One striking thing I remember is that the woman asked him in what language he thinks, and he answered that he thought in English…but always made love in French (Aaaaaaaaaah! *faints from heat*). I don’t remember what the conflict was, but he seemed to have some beef with people in France. He and his other male friends belonged to an elite club, but I’m not sure if they were spies because the hero has some level of PTSD from…something. They did belong to a fencing club, I think. I don’t remember the girl’s circumstances. But they do grow to love and respect one another. They never had a hate to love relationship. I think the girl just wanted to please the, guy but didn’t always know how to. The couple makes an appearance in the other novels.
I only read a preview of the third or fourth book. It took place in a location outside of England. There could have been a harem involved, but the main characters were still English.
Please help me if you can. Every year, I try to hunt for this book to no avail. I hope I can get some hints here.
Can we solve this for A.D.?

That sounds a bit like The Seducers Series by Madeline Hunter – there’s a singer heroine in the second of the series and all the heroes belong to a fencing club. At least two of the heroes are half French (surname Duclairc, IIRC).
The first of the series was published in 2003, so the timings would fit.
jcscot, that’s what I was thinking! But it had been so long since I’ve read it, I couldn’t be sure.
I know I don’t have the answer to this HABO, but if you’re looking for an Englishman who makes love in French, allow me to recommend Lord Peter Wimsey. He pines and smolders like anything (I love him) and it is said of him: “il tenait son lit en Grand Monarque et s’y démenait en Grand Turc.” Corroborative evidence — after the slow burn by which I measure all slow burns — is given.
This definitely sounds like The Seducer Series by Madeline Hunter. The first book mentioned sounds closest to The Saint. The second book mentioned could be The Seducer, the first book, but I’m not positive based on the description. I have only read The Seducer and The Romantic.
I, too, only make love in French. This might go better for me if I knew any French words besides “fromage.”
I have read this! It is all very familiar, but I can’t quite remember… might it be Midsummer Delights by Eloisa James?
Hi! Thank you so much. I am overwhelmed. I should never have doubted this place. I’m at a loss for words. I can finally sleep with ease. I’m on the way to ordering them.
best,
AD
jcscot and Veronica: those are the very ones. Damn. The saint even has a blue cover, which is vaguely familiar.
Marnie: Thanks…but the series centers around men and not women…but it looks interesting and I will not pass up a chance to add that to the collection.
Lucy and Jingle: Oh my word!
Yay!!! Usually when I know the book, there’s at least a dozen members of the Bitchery who’ve got there before me, so I’m delighted to have got in first for once!
Jcscot: you are making your way to the top, such is progress! this place is called the Bitchery? Holy crap, I’m learning so much!
best,