I'm not into the idea of being cucked by either another guy or a dog or a horse or a boar, but I do get off on the idea and sight of watching a woman getting fucked and creampied by either one of the 3 (or a combination of the 3). But then I'd want sloppy seconds with her after watching her getting filled by the guest.
It's only cuckoldry if I'm denied sex with the partner, but if I get a turn, I just see it as a "gangbang" or "group sex." And I would not be in a relationship with someone if they're actively trying to coerce me into cuckold status, but I would love to be in a relationship with a woman that would let me have her after watching another man or either a dog, stallion, or boar pump his seed into her and lets me use the other party's cum as lube.
If others want to be cucked, then let them, but it's not for me.