I respectfully disagree. I do not think it would be a good idea to put your horse in the care of someone who could end up hating you tomorrow. You wouldn't want this girl's attitude toward you to affect the care of your horse. Even if you are right next door and therefore could ensure your horse never went without food etc., horse riding/owning is supposed to be a fun experience, you wouldn't want it tainted by the atmosphere. Also, this would be your first horse, it would be much better for you to keep this horse in a boarding barn at least for the first couple of months to a year so that you can learn from more experienced horse-owners.