It will be easier for you if you come married; otherwise there is no guarantee that you can find a job here/get employment.
That said, there are jobs around here, so I feel confident you could find something here if you came. But Qatar, being an Islamic country, is kind of touchy (read: intolerant) about unmarried people living together, etc. While they generally used to leave westerners to do their own thing, recently they've been cracking down on stuff so I would recommend that you guys come in together as a married couple if you want to join him here.