There is no correlation between number of sex partners and propensity to cheat. Whoever this guy is who asked you this question with this intention was very creative,
The number of sexual partners is not directly proportionate to your inclination to cheat. Good Grief! I would probe to see if I could find out where his insecurities come from, has he been cheated on before? But I have to admit, if he persisted with wanting to know and could not get past it I would not continue to see him.
YG
http://twodatediva.blogspot.com/
YG
http://twodatediva.blogspot.com/
Z