Unusual_Bulge said:
P(A or B) = P(A) + P(B) - P(A and B)
This is better than the first equation.
But this equation also assumes that the human capacity for love is limited to one person.
Also I believe the probability of cheating dependent on the magnitude of love felt for the person. That B is a function of A
B=f(A) I think it is an inverse relationship. The more you love the less likely you are to cheat.
A simplified coefficient of cheating would be the proportionality of hotness of the gf and the non-gf.
so B = (H[non-gf]/H[gf])/A
The limiting cases: Your GF is not very hot and you don't love here much. In this case B approaches infinity (probabilistically 1)
Your GF is hot and you love her a great deal. In this case B approaches 0.
A more complete equation would including a drunk factor and an opportunity factor.
Happy Algebra
p.s Sex=Fun [http://files.sharenator.com/sexisfun-s320x518-914-580.jpg] Proof!