Well I just got a new filly that I know nothing of her background.
She does nothing but pace and winny all day. Even when she's around other horses.
She's only on hay and gets it 24/7 . If you go pet her she loves it and nickers and grooms you, when you leave she'll run into the fence and run back and forth and scream.
I've seen it, felt it, had a horse that would rather be with me than the herd. He was a rare exception, and I think some are more "capable" of expressing "human like" emotions and behaviors, especially untrained ones, than others.
My old man Rooster was one in a bizallion. He wanted nothing to do with other horses, unless it was to run them out of his "space". He rarely ever messed with them, and he was top dog, not at the bottom. He would stand by the fence for hours upon hours waiting for me to come out, he wasn't waiting for food either because he was only fed hay and pasture for years and I don't do treats. Anyone could ride him bareback and with just a rope, I have many many stories of him risking his safety or sanity to keep a person on. One time he took a giant tom turkey full in the face in a flat out gallop with me on bareback and didn't miss a step, I was more startled than him! In his last years I let him live in the yard and on the porch! He would stand for hours looking in the windows watching me and the TV. He napped with his nose resting on the door handle. My kid could crawl all over him, and he wouldn't so much as swish a fly. I miss him so much, the day I put him down still haunts me and I bawl every time I think about him, had him for almost 20 years. I miss him so much.
What an amazing story and priceless photo, fly! What a trully special boy he must have been.
To the OP, there is no doubt in my mind that a horse can love. You can't measure it (love) within the human species, so I don't find it surprising that you can't for horse-human relationships. Horses are more honest, though..so I believe them when their actions show me their love. :)
I put my appyX mare on family pasture. She waited by the gate she was loaded just inside of for a solid month before she gave up. Wind, rain or shine...she waited. It really broke my heart. I was not there, family told me about it as it became something of a local conversation.
Yes, horses are so different from us that many might think that they are not capable to feel emotions like we do - but, although they might not get the human concept of love, I firmly believe that they have their own and that they are able to recognize, if a person loves them.
Not that long ago, there were firm believers in the assumption that different races are not capable for feeling emotions or understanding different concepts... We now all know it is completely absurd and untrue. Why should it be different with horses? By learning to understand them not only as "just animals", but also as slightly different equals, we can open to a new experience of the love that horses offer.
I don't know, maybe in different circumstances, I wouldn't agree to this opinion. But my horse, Snickers, has taught me otherwise. He might be one of a kind, he is very bonding and shows great affection towards me, and the things he does and the attitude he shows proves only love to me - but, since I saw that in him, I see it also in other horses and how they act around "their" people. I could not describe it very well, because it is something more to feel, than to describe. Like we feel when being near a person who truly loves us - we might not be able to put it in words, but we all know the feeling when whe encounter it.
I don't know the technical answer to this question. I don't know that much about psychology.
But what I assume is that horses do feel love, but it is not the same as human love... I'd definitely say it's equivalent though. I mean, when you think about it, horses understand how to do very complicated riding movements, they know how to do lead changes and piaffes, what makes us think they couldn't know love either? When a mare nurses her foal, that is love. I know I feel love and connection for my mare because even when she was uncomfortable or in pain she would be strong and try to push through it for me.
Heck people, define love! Do you love your parents the same as your siblings or your children? Or the same as your spouse? What about your dearest friends? And your pets or horses? Or, and not really joking, how you might love an activity or a sight or God or country?
Of course horses love. Just like all of the above, it may be different from horse to horse and person to person and different from every other kind of love, but that doesn't mean it's not there. Just that it's different.
I know my horse loves me as surely as my dogs and cats and family and friends all do in their different ways. Yes, my horse is far more likely to accidentally kill me in a burst of fear or attitude than my sister or my cat is, but that is beside the point. To attribute compassion, patience, kindness, irritation, stubbornness and all the rest we do but deny love seems foolish to me. And just as I don't love every other human or horse I work with, I don't expect every horse loves every human, but sometimes that warmth is certainly there.
You know how some people are "animal people" and have an innate ease with which they communicate with animals? Some people are gifted in their ability to tap into a horse's mind and understand them even though they are different than us.
I think some horses are "people horses" and innately communicate on a more advance or different level with people, just like some people can do with horses. We've made "anthropomorphize" a bad word. Why? Are we humans really so different than other animals on such a basic level there are no longer any emotional similarities? I know some people will deny animals even have emotions. Maybe those "human traits" we fear assigning to horses aren't really human traits at all. Maybe all animals have variations of emotion that they express in a different way than us.
We are so different from animals, especially horses. (In fact, we are more dissimilar to horses than we are to most other "pet" animals.) I wouldn't be surprised if we didn't see or couldn't understand everything that's going on between horses (and between horses and people.)