Oh, come on. Your human isn't your significant other if you're giving him up for a horse, is he? I cannot believe a horse would be the reason a couple would break up. One of the problems, yes. But not the sole reason a couple breaks up.
If you're talking about breaking up with a boyfriend or girlfriend because they don't share your interests in things like horses that's one thing. It's a whole 'nother thing to end a marriage, especially with children involved.
If you're spending so much time with your horses that your husband/boyfriend, etc., says you're spending obsessing then I think it's important to evaluate your behavior.
I doubt, though, that horses are commonly the sole cause of a relationship's end.
Are you absolutely sure you wanna mess with my carrots?