It is certainly possible that XMRV can be caught the way you describe. We don't know yet the routes of transmission or the likelihood of infection via those routes. However, I'd like to point out that the chance of a male catching HIV or HTLV from a female due to "normal" unprotected sex is very very small - unless there is an open cut or something that allows direct blood to infected fluid contact. It does happen, yes, but its far from a certain thing. Its even a pretty small chance going the other way, from infected male to female - although more likely than from female to male. XMRV might be easier to transmit via sex, or even via other bodily fluids that are exchanged during intimate contact, we don't know yet.
Either way, it sucks to be sick and not know why. So I wish you luck in finding the cause. It couldn't hurt to be tested for XMRV, especially when they agree upon a reliable testing methodology. Right now there is just one lab doing it, and the blood working group is trying to sort out which assay is the best.