Mathematician:
If you love someone, Set her free....
If she ever comes back, 1 + 1 = 2 (peanut!),
If she doesn't, Y=2X-log (0.46Y^2+(cos(52/34X))x 5Y^(- 0.5)c) where c is the infinite constant of no turning point.....

Statisticians:
If you love someone, Set her free … If she loves you, the probability of her coming back is high
If she doesn't, the Weibull distribution and your relation were improbable anyway.

Physicist:
If you love someone, Set her free....
If she ever comes back, it's the law of gravity,
If she doesn't, either there's friction higher than the force or the angle of collision between two objects did not synchronize at the right angle.

Nowadays' style:
If You Love Someone, Set it free …
If It Comes Back, It is yours If It Doesn't, Hunt it down and Kill it...!!! OR PERHAPS REPORT TO IMMIGRATION THAT SHE/HE IS AN ILLEGAL