"All is fair in love and war", a phrase credited to poet John Lyly. I'd have to disagree with the sentiment that all is fair... but I will say that certainly all things associated with war, at least metaphorically, are possible in love.
We can fight all night only to wake up the next morning with the collateral damage strewn around our hearts, only to have forgotten why we were fighting in the first place. We're then left only with the knowledge of what it is we're fighting for... the love itself.
We attempt to rescue love for the grips of insecurity, selfishness and doubt... and it can be an all out battle to get our needs met while meeting the needs of the object of our affection. One thing is clear, we only end up hurting ourselves when we hurt the ones we love.