They didn't know each other before the shipwreck, but he did know who she was...
At the beginning it was hard, but as time passed, this guy learnt how to provide food and shelter, he started taking care of her, and eventually she started caring about him... after all, there wasn't anybody else in the island...
He eventually built a cabin, had a functioning automatic potable water supply, and all sorts of little clever commodities, all done to make her life easier... it was the most effort any man had ever done for her, and all the hard work made...