I would be very offended if my partner said he wasn't a fan of my curls and insisted I straighten my hair. If you love wearing your hair curly, he should respect that. Your curls are a part of you and if he wants to change that aspect of you, and you give in, what else will he insist you change to please him? You could politely point out how hurt you feel and ask him how he would like it if you remarked on something about his appearance you didn't like and asked him to change it against his will. (Hopefully this might make him realise and think twice!)

Best wishes.
UK Curly
Curl type : Boticelli, 3a, loose curls
Porosity : High
Texture : Fine/medium (I think!)
Co-wash/rinse out/leave in : L'oreal Full Restore 5, GFR&S, Schwarzkopf Bio Pomegranite
Gels : Umberto Giannini Flirty Curls Scrunching Jelly
Finish product : Boots Naked Style Frizz Fighter Serum or a pea-sized blob of condish smoothed over canopy
CG since Feb 2011