Right now the best that your boyfriend can do is to come to the U.S. on visa waiver several times a year, or get a B1 visa, and come here back and forth for two or three trips a year. A visitor visa can allow him to remain here for up to six months,which can be extended while in country as long as his total stay does not exceed 1 year.
If he has a BS degree or higher or equivalent, he may be able to get accepted by an employer who will sponsor him in a work visa of some type. Depending on his degree he may be eligible for H-1B or O visa (masters or PHD)
He can also explore cultural exchange programs.
The H-1B may be oversubscribed, but if he works for a research organizatgion that is non-profit, he can still get an HN-1B visa.
He has to have a job offer to get a work visa.
With language skills he may be eligible for the seasonal work visas, but those are oversubscribed right now as well.
His best bet for an employment based visa is to try to find an employer now, and have the employer sponsor him this next April when the H-1B program will be opened up again.
Of course he can marry you in the Uk or your own country, and then you can bring him her as a family member of a student.