Hello Annalynn,
I am an American who went back and forth between Spain and the US for years before finally marrying my Spanish boyfriend in order to be able to work.
What am I essentially saying? You are out of luck, at least on the getting a visa via a job front. The only way to get a work visa is if you are some engineer or something that some Spanish company really needs, they would have to sponser you, it would cost them money, they would have to wait months for you, so it would have to be worth it for them. Unless you have some special highly demanded job that merits Spain hiring you over any other EU member (yes, they have to show that they tried to place ANY EU member first) you are out of luck, welcome to the club. Sometimes, SOMETIMES you could get a visa for being an English teacher, but not so easy either, remember there are lots of English people that require no paperwork.
Your best bet for a year visa? A student visa. Enroll in school, language or whatever… they will send you a letter of invitation and you will have to get a student visa for Spain (sorry, it is also a huge pain in the butt… ) but it will allow you to stay in Spain for more than 3 months…
It used to be really easy for an American to overstay his/her legal limit, they never asked questions in the airports, but recently it is starting to get a bit stricter and I have heard of Americans being sent home for overstaying their 3 month limit. So better safe than sorry, I would get a visa.
If you and your boyfriend were to get married I think that his work visa would give you the right to stay in Spain, but you would have to check that out with a Spanish embassy first.