My general bias is that horses have a logical reason in their own mind for everything they do. I really dislike when people say horses have an "attitude problem," or similar phrases like "my horse is being bad," etc. I believe horses are extremely smart, but I don't think they have the complex thought patterns that humans do. I seriously doubt your horse is thinking, "I sure haven't seen her in awhile, I wish she would come and spend more time with me so we could build a real relationship together." More likely, your horse has a simple reason for not wanting to get caught. It might be related to not wanting to be separated from the herd and worked alone, or it might be that since you only go once a week that you take him out and work him really hard. Horses enjoy exercise, but only when it is "fair" work and the horse is in shape for the level of work he is doing. If you gradually get a horse used to going on rides or exercising alone, and build up his muscles gradually, he will be happy to leave the pasture to work. Especially if you throw in a few days where you only do pleasant things like hand grazing, grooming, or working on leading. But if you always take your horse out and work him hard, especially if you are always doing new things he doesn't understand, he will not want to get caught. I have seen lots of horses where the owners grab a horse out of the pasture, lunge hard or ride hard for an hour or two, and throw the horse back out. It doesn't take long before the horses won't let the owners catch them anymore.