It's nice to hear that you own and care this much about them both. I'm really happy to hear that they are important family members rather than just pets.
If the female won't stand for him, there's not a thing anyone can do to change her mind. Mother nature has control over this. Even the dog doesn't have a clue as to why she thinks she wants him, then doesn't allow him.
Since they live together you might just want to leave things be and happen in due time, although monitoring them is important in order to be sure there's no fighting (this too would be by nature, not by their choice) and to note when a tie occurs (in order to determine a due date).
The male may just need some more maturity.
As an owner of an animal rescue org, I have to mention that there's a higher risk of disease, a shorter lifespan overall and other health complications in intact dogs (non spayed/neutered). This is something that many owners don't realize and once their companion develops cancer or something else, they wish someone told them when they still had time to make things different.
Look at this http://www.peteducation.com/article.cfm?cls=2&cat=1625&articleid=911 and this one is pretty important too http://www.hppl.org/BasicNeuteringInfo.htm
If you didn't know this, it may make a big difference.
Good luck either way and really, keep up the good work!