There have been a number of threads discussing if horses can feel love for a human. I'm agnostic. They certainly feel some sort of affection, but their minds are not wired like ours.
We tend to think that if I love X, X will love me back. That doesn't work with humans, let alone horses. We also tend to think that if we love an animal, or if the animal loves us, then it will behave in an unnatural way to show its love. And that usually doesn't work either.
George Adamson, of Born Free fame, loved the lions he worked with, but he knew they remained lions. When old, he hurt himself while out with one of his favorite lions. The lion attacked him, and only a 3-shot revolver kept him alive. IIRC, his third shot grazed the lion and scared him off. Adamson blamed himself for the attack, saying it was what he deserved for turning his back on a lion while showing injured behavior.
When we work with animals, we need to understand that they remain animals, with very different emotions and strongly embedded instinctive behaviors that easily override any feelings of affection they may have for a human.
None of this is meant as a criticism of Jessice Forsyth. It is just a reminder that horses will always be horses, and it isn't fair for us to expect them to adopt human standards of behavior and emotion. It is our responsibility to learn about them and work with THEIR abilities, rather than expect them to remake themselves in our image.
As a trainer I know says, you have to love them for what they are, not for what they cannot be.