If you want more depth or just different flavor to your werewolves you have to either dig the origins of the European tradition or look for alternatives outside, like native American benevolent shape-shifters.
European werewolves predate christianity.
Witchers or shamans (for a lack of better word, especially as it must meaningfully differ from the "wise wizard" priests) of the once widespread tradition (spanning from modern European Russia to Germany, to northern Italy) still partially preserved by Baltic so called 'pagans' (we're not pagan by definition of the word; title "God" is never used in plural, but it gets complicated from there) on certain nights turned into wolves to...
...mount raids on Hell itself, to rescue goods, livestock (and possibly human souls?) unlawfully taken there by its inhabitants (whoever they are).
It's a tradition possibly, at least probably, closely related to the practice of berserker warriors, who were spiritual practitioners able to enter controlled state of affect letting them bypass checks and balances normally imposed by 'intellectual' conciousness allowing them to appear significantly faster, stronger and aggressive than any normal adult human (children and animals can do that naturally).
Practice of either might have resulted in slaughtering livestock in inhumane, gruesome ways, and not necessarily livestock belonging to the practitioner...
Modern elite warriors reach comparable results by extensive training and conditioning. Knowing those guys are indeed training to almost literally go to hell and expect to return victorious, it's little surprise The Special Tasks Unit of the National Armed Forces of Latvia feature warrior wearing wolf's hide on its crest.
Random history lesson aside and back to your story, and sexually concerned pack werewolves, how you describe the main 'hero' already commanding a harem, and the she-wolf-girl as alpha, its almost by definition there's no permanent union is possible without breaking one. Respectful alliance is, but her becoming prime in his harem is as unlikely as him becoming prime in hers -- neither is a true alpha role. However, that's what being the designated mate would likely mean.
The whole mate thing, she's just identified a male who would make her offsprings stronger and better warriors. Him being an established alpha male himself isn't surprising, even if somewhat unfortunate.
In real world wolves, females do lead packs. While the hierarchy is determined by force first and merits second, an older, wise, cunning bitch can still command enough authority. Then, woves packs do have much more complex structure than plain hierarchy, even prime meat-bringer can not be always the leader, but as far down as third or fourth tier, lesser than "advocate" (or judge) who terminate minor conflicts without involving the alpha. Wandering independent males are a thing. In some occasions, they don't mind killing small clubs of a newfound mate, just to make their own few months sooner.
Then, in another aside, the whole craze about virginity is, that the first male that plants his seed in a female somehow magically influences all her future offsprings, even if the copulation in question doesn't result in children on itself and the eventual offspring are sired by someone else, they're still somehow, at least partially, are supposed to be children of the First. (Now, think about prime nocturne rights of feudal lords in this light, it suddenly makes sense.)
While this (unscientific) attitude is largely rooted out in humans, it still exists as a superstition in dog breeding communities: a bitch 'tainted' by the non-breed dog is considered impure and unsuitable for future bloodline continuation. By some stretch, in a supernatural infested world, the werewolves might hold similar views.
So, our alpha bitch is looking not just for a mate, but for her First. While she would be happy to have him as lieutenant and harem prime, it is not on itself a requirement. Being permanently involved in his harem is not an option; she have her own pack to lead, expecting to inherit it from her father... perhaps, sooner than he thinks, or so she believes. God knows why, but getting her own First is a big step in that. Maybe daddy have a preferred partner for her she doesn't approve (it might even be himself, but not necessarily). Maybe, she's in race conditions with a brother. Maybe both.
Our hero have her as his captive, and calling her father insert himself in ongoing conflict he knows nothing about. Daddy has every reason to assume hero has taken his daughter already. While unfortunate, it does serve at least a subset of his goals, particularly, in denying the rebellious daughter a chance to take over the pack, or so he thinks. She, however, isn't interested to disprove it either. So, as far the werewolves are concerned, they are mated already, even if nothing had actually happened.
Now how it can go, I think he is eventually helping her to take over her pack from his father, perhaps reluctantly or even unknowingly, and they end up forming alliance of independent forces, but not before him refusing (or even curing, by powers of her existing harem) an offer (or attempt) of being turned and included in her pack.
Perhaps, they do have sex at some point, perhaps in highly ritualistic situation, but no real intimate relationship.
