Ok so im bumbling around the great bazaar in Mournhold and I meet this guy...his name is Fons Beren and he seemed to be a bit of a turd but I didn't care...I set him up with this woman called Marena or something and hes preparing to go on a date with her...I have recently learned that by setting marena up with the guy in the trade shop you get the bipolar blade...is there someway I can set her up with the trader instead...I tried killing Fons while he was preparing but she still seemed excited about meeting him, the Dunmer frown upon necromantic sorcery wonder what their stances on necrophilia are...hrmmm but anyway, if anyone can shed light on this then it's much appreciated

Short of restoring an old save, then no, once you have committed one man to Marena, then there is no way of changing.

Ah wow thanks (that was quick)...uh does this then mean that I cannot get the bipolar blade?

nah it's ok thanks...I'll just cry and go about my life worrying about commiting Marena to a life of hell with The Fons
thanks anyway