What does the quote " All's fair in love and war." mean?

Question

I saw it on someone's 360 page.

Answer 1

there are no rules to guide you in love or war...anything goes.

Answer 2

it means love and war are both irrational acts; therefore, there is really no rulebook for them - people will do what they got to do - any means necessary - so all is "fair"

Answer 3

It means more twoard fighting war is hatered an love is well you understand.  One minute you can not like each other the other you can.

Answer 4

Basically it means that in certain situations (ie love and war) you aren't bound by the rules of fair play... or something along those lines...

People generally use it to justify cheating.