i've had to cut a couple loose before over not skiing, or sucking at it. It wasn't the exact problem, but it just creates bigger problems or brings underlying character flaws to the surface.
the first one....did nothing but brag about how good of a snowboarder he was (which is annoying to begin with).....we took one run together and then he wanted to leave because i could ski better than he rode, and i think he was embarassed. personally, at the time, i didn't care, i just wanted to spend time with him on the hill. but turns out he was a jerk and that was the catalayst for the demise of the whole relationship.
the second time...he didnt ski at all...in fact he hated skiers because to him they represented the rich assholes he grew up around and hated (and this was a theme of his personality....super negativity). The first year we were dating i didnt ski much...it was my first year at college and i didn't have time or anyone to go with....but the next year when i joined the ski team and had all these new ski friends that i found more interesting and less negative........yeah....the relationship fell apart.