Everything is fair in love and war !! Really ??

Everything is fair in love and war !! Heard this line and used it also several times during arguments. But last few days actually got me thinking about it. A friend of mine just broke off her 7 year old relationship. That too when after so many years carrying it out covertly she had finally confessed to her parents and all. Reason being that the guy was lying to her for the past 7 years about his caste. Anyone reading this would feel that the girl is a cold hearted ,archaic, conservative person ,who still believes in caste prejudices. (These days its an anathema to any modern day secularist....and most of us see ourselves in this category ). But knowing her well I know its not the matter of caste but of trust. Seven years this guy was lying to her (according to the guy this is the only issue he ever lied on ).
However if I try seeing it from the guy's perspective he did it so that he doesn't loose her. In the end also he was not willing to tell her but did so only when he realised she would get to know herself. His idea was that he would confess after marriage and then she would anyways understand .His argument that everything is fair in love and war. Actually this is what has been shown in several Hindi movies too. The guy lies right through...gets the girl and in the end come out clean and the girl understands. She is supposed to be in love with him right...so she should understand that it was only done to get her.
This got me thinking about what actually is love? Does love mean to covet, to possess by whatever means or does it actually entails trust and understanding. When I talked to a few other of my girlfriends they shared my opinion that here the issue is of trust. Do the guys also see this the same way ?
I really don't know the answer to this.
If the girl had forgiven him too and they would have continued their relationship will she actually would have been able to forget. And how do you again trust a person? Every time something turns up ,wouldn't she be reminded of the past that once this guy has lied for 7 years. Trust once broken can it ever be restored fully... I doubt. Also this got me thinking about this guy, his attitude towards life. For him end is important ,the means can actually go to hell. So when life will present other travails in front of him what will he do ...take the easy way out..lie, cheat so that the work at present gets done..future repercussions who cares? But then this is the attitude which is gaining mileage these days. Values look like a cumbersome burden to people. Honesty , Trust are these just empty words now ?
Again no answers.