Hi Liv, and welcome to the forum.

I don't have any experience with the Spanish, but what you've been told sounds remarkably like what I was told when trying to get into France to join my (then) boyfriend. At that time, the consulate in Stuttgart would not take a visa application (of any sort) unless you had a job offer (in French) to go with it.

If you had the job offer, you should be able to go through the Spanish consulate in London (based on your residence there). If you are "serious" with this guy, you might want to consider getting married - though even that won't guarantee you a visa (never mind one with immediate working privileges - those often take a year or two of marriage).

Have you looked into your job prospects in Madrid? If you could get an employer seriously interested in hiring you, you might be able to work out the rest of the issues (though the 4 month time frame for processing a visa sounds about right). Wish I had better news -but perhaps one of our Spanish expats will know of other alternatives.
Cheers,
Bev