Send to trainer or not bother?

The problem with the hands-off "send to the trainer" approach is that although the horse may improve greatly when the trainer trains/rides, he will revert to his old behavior if you don't learn along with him. It doesn't sound like you don't have time for that.

On the other hand, if the trainer can give the horse a tune up and then promptly start working with the both of you together, not only will you end up with a good horse but you yourself will become a much better rider. Yeah, you are in school and don't seem to have time but when you get out of school, you will still be a rank beginners and beginners easily ruin horses, even the "beginner safe" ones. Do you want to learn to ride properly now or later?

I would also say that for $1500 a month, you should be getting a world championship level trainer. A back yard (hopefully good) type of trainer should only be about $800 at most.

Don't marry the horse.

he was never going to be a beginner horse, not at 6 years old.

Let him go to someone who does have the background to do something with him- you don't need to wreck his young life to satisfy your need to own an animal- just LEASE a beginner horse, and someday when you have a degree and a career, you can decide whether you want to own.

In fact, the best way to find the right horse is to lease one, and find one you actually do well on. A lot of well schooled horses are leased out so they have enough work to keep them in good shape, but not so much that they get broken down. Trust me, some of your happiest hours will happen there.

Let the 6 year old go down the road. You don't belong together, and he'll be dangerous and bored, and destined for dogmeat if you try to prove me wrong.You both have better things to do with your money and his life.

Some horses are never suited for a beginner, regardless of training put in. No way to know until the training is done. I'd recommend selling him to someone experienced who wants a project and getting an older horse whose more suited to your skills. There's no point in keeping him if you can't ride him. He'll be much happier with someone who can use him and keep him in regular work. He'll not enjoy sitting in a pasture his whole life.

This sounds like a horse not getting enough work.