Question about Nordanner breeding limits/reasons

As some of you know, I was a writer first, and though I've dropped it for the past 15 years or so, I'd like to get back into it, and the addition of prose to Nordanner kaaring, as well as my purchase of Lord Rahl, has sparked inspiration.

He has used all his slots, or has them spoken for, but has never fulfilled a wish of his that was mentioned on his very first reference, the he 'likes blond mares'. I have a champagne mare who would probably be his 'type', but unlike regular stallions, who can breed as many mares as their stamina will allow, he's limited until he hits 200(which his story should help him achieve). I'd imagine that this would be a frustration, and therefore source for conflict and plot, for him, but I'm not sure what can be a canonical reason he can't breed Maya. He's a hotblooded stallion used to getting his own way, he wouldn't take, 'because they said so' for an answer. Would his owners be feeding him a drug to keep him impotent(except when those last slots are used) until more slots open up? Or is it a spell from the same Skagenrak wizards who created the potions? Or something else?

Don't get me wrong, I'm not trying to violate breeding rules here, just trying to create a reason for the conflict in his story, as I'm going to have Maya take a shine to him as well, and it would be nice to get a 'star-crossed lovers' storyline going.

I already have his plotline with James sketched out, wherein he was purchased as gift for James by Deana, and James was like, 'you bought me a stallion who has spent his life as a stud, with no show experience and minimal training, for how much?!' to which Deana replied, 'He's big, he's strong, he's aggressive, he has no previous training to get over, teach him to joust.' So we have Rahl behaving like the valuable stud he was, who never worked a day in his life, versus James, who is a down-to-earth sort who has always worked hard, trying to give him a show career.

But, since I'm a glutton for punishment, I want a plot going with Rahl and the other horses too.