I had my hip replaced 8 weeks ago...Not quite the same as a broken femur, but I am sure that it is similar in recovery (because they sawed off the top of my femur in surgery). Anyway, I can relate my experience to you... But, what I have learned through all of this, is that everyone is different. Every doctor approaches recovery differently, every body heals at a different rate and with different symptoms, and every person reacts differently to it all. So your boyfriends experience will be like no one elses...Just his own.
By 6 weeks there is visible bone growth. I am assuming that he will be pretty light weight bearing for the first month or so, to give his bones time to fill in. He will be amazed how much stronger his bones feel after 2 months. But it does take time, and it is important that he gives his bones this time to heal. If he pushes his weight bearing limit or activity level before those bones are fully healed, he could rebreak it...Which means that he would stand a chance of them not healing properly. The good news is that, if his bones heal properly, they will be stronger than ever. (so future sports shouldn't be a problem).
There is alot of soft tissue damage done to the leg during a surgery that involves the femur. This will take some time to heal, and then some more time for physical therapy to work. He will regain it all back, but it will take a lot of work, and most importantly patience.
He does indeed have youth on his side. The body heals so much faster when you are young. He also seems to have a very caring girlfriend, and that support will mean alot. For right now, he is only 2 days out of this ordeal. Of course he's not excited about physical therapy. I realize that they make you get up and do a little bit each day right away...But it is hard, and all you really want to do is rest and recover. As long as he does what he is told, and has patience, i'm sure he will heal just fine.
If this helps put his and your mind at ease about the future, I will share a bit of my story...I had 5 surgeries on my hips between the ages of 13 and 14. I spent a good year either in a wheel chair or on crutches. But, when I was 15 and done with all of it, I was healthier than ever...I even joined track and ran cross-country. So, be patient and have faith...His future is still whatever he wants it to be.
Hope this helps...
Barbara