My instructor worked virtually a whole summer with me on cross wind landings. I simply could not get them right. Then we changed aircraft (C152 to an older C172) and suddenly I had no difficulty at all! Looking back on it, although I was unaware of it at the time, loosing sight of the runway during the flare was the problem for me. Once I got it, X wind landings were never again an issue.
My point is, as so many have said earlier; encourage your pal to change either the instructor, or the aircraft. If he really wants to progress, he needs get past his ‘block’, and either should do the trick.
Regards,
White Bear.