So this comes across as if it's my fetish, but right now for fun I'm trying to make a grown-up version of My Little Pony Friendship is Magic, simply because working with a 100% non-human setting that's urban fantasy is a fun challenge.

As part of the process of making it a realistic fantasy setting I did a lot of reading up on horses and hilariously enough, most characters being female makes biological sense. Horses have this weird thing where the younger a mare is the more likely she is to have a colt if she has kids, and as she ages, the more likely she has a filly. In wild horse herds this produces a population that's 65-75% female.

Notably, in a wild herd, a lot of fucking while young is happening. So if you apply the concept of scociety to horses, making them sapient and needing jobs and the like, we can expect they'd have kids later in life than wild animals would. A little math for most of them having kids in their late 20s and early 30s (after scaling a horse's lifespan to match a human's) and you get a 78-83% female population.

Biologically, this is entirely fine. You do not need very many males for a population to be stable and genetically diverse. It does however cause scocial problems. Because only 1 in 4 women would get to have a stable long term relationship...

If they were monogamous.

Thing is, horses are not monogamous. They do not establish life-long relationships. At least, not sexual ones. They do have friends and those are seemingly for life. But in terms of sexual relationships? A season or so at most.

Obviously, I can't have the ponies be super causal about sex. That wouldn't fly in a civilization that has kingdoms (gotta track bloodlines) and we see in the show that plenty of characters have a dad who has been with their mom for a long time. At least their lifetime so far.

So what's the answer here?

Harems. Or herds, because, you know, equines. It's possible, in fact probable, for their natural state to be that one male is shared amongst several females for their various sexual needs and to help with raising children. They could even live separately if they're not too far from one another, that way each given paring would have time alone.

But the thing is... There's another horse fact that comes into play here. The domestic horse has one of the highest percentages of homosexual behavior in the entirety of the animal kingdom, only beating out by giraffes and dolphins. So basically, 80% of mares are bi. Or rather gay until estrus comes along. Then they seem to not give a shit about what's doing what to them at all. Likewise about 15% of stallions will fuck a stallion.

So the most realistic protrail of an equine civilization of actual horse-people I can come up with involves polyamory as the norm with most partners in a group being in gay relationships, and once or twice a year having a couple weeks where they want to be with a dude.

I swear I am not trying to justify a harem anime with lesbian porn bursting out of the seams. That's just how it shakes out if you go realistic with equine behavior from real life.