I don't see anything suspicious in saying that this is the first time you thought of it. My understanding is that his dogs have only been mature a year or two at most.
Him: What do you think about helping our dogs get off during their heats?
Her: What makes you think we need to do that?
Him: I feel like they're almost being tortured when they're in heat, because their needs aren't being met and they're humping each other.
Her: Haven't they been sexually mature for years now? I mean, one is like 9 or 10 right? What's different now from then?
Him: "this is the first time I thought of it."
Her:So you've been watching them be "tortured" for years and only now you feel like helping them? i.e., Wtf, you're lying or you're a POS if you're telling the truth.
That's just one random example, but I can't think of anyone that would be asked such an usual question from their SO and not think about it. A, "sure yeah, that's fine" is highly unlikely and the most likely end to the conversation I could see would be, "we can talk to the vet about it." In which case, I don't think many vets would say it's normal or necessary to do it.
Tons of variables and unknowns, but it just seems like bringing it up wouldn't lead anywhere.
Simply put, raising this idea once is not nearly enough to raise any serious suspicions unless his wife is an ardent member of some anti-zoo group.
Agreed. Once is worth a shot.
I'll grant that he really ought to have talked about this before getting married, but there's no use crying over spilled milk. The best he can do now is carefully feel her out, and yes, abandon the idea of ever telling her if it seems like she could not accept such a thing. But before giving up all hope, an effort should be made.
Meant to make this point before but forgot, but once again, I agree. Coulda, shoulda, woulda, don't matter.