Pocahuntus is a love story- the war is just context.
That's like saying 'how did they get away with making Dear John a chick flick, given that it's set during the Iraq War?'
Obviously you've got to have some historical distance but if you took Jim Cameron's Titanic slimmed it down, cut out the slightly naughty and violent bits and turned it into a Disney cartoon, it'd fit in great. Rose is Belle, Jack is Aladdin (i'll be honest I don't know Disney very well), the mean guy is the Wicked Witch, Bernard Hill is the candlestick...etc.
Either this question came to you whilst you were having a very hot bath or you totally misunderstand the way audience demographics work.