I don't know, you're not a Cancer. One is fire, one is water. Not a good mix. Maybe this will help, in case he asks.

SAGITTARIUS AND CANCER
Cancer's sensuality and romantic imagination intrigues inquiring Sagittarius. But Sagittarius is both venturesome and cerebral while Cancer is cautious and emotional. and this pair will never understand each other. Sagittarius can't supply the security and stability Cancer needs or endure Cancer's moodiness and jealousy. Without even being aware of it, blunt Sagittarius wounds sensitive Cancer at every turn. When Sagittarius seeks outside stimulation away from home, Cancer nags and whines and tries to hold on tighter. They'd be better as just friends.


SAGITTARIUS AND ARIES
Both share a similar approach to sex (they make the most of every opportunity). Add to this a mutual love of the outdoors and a fondness for socializing, and you can see why they get along. They're also intellectually well suited: Both have a wide range of interests and love to talk about them. Sagittarius is more philosophical about problems than Aries, who becomes more personally involved. The one question mark is their combustible temper. Arguments are heated but short-lived -and the making up will be fun. A perfect match.