What matters changes at different point of times in everyone's life. It depends upon many things which are not in anyone's control at all the times. Do not get worried if you feel that you are not being prioritized by someone, who earlier probably did. Try to understand the world of him that has changed him around, try also to be back in it if you really wish to get back to his life. Try your maximum but with a prior understanding that it might or might not work!
Celebrate your success if you can get through and if not, take it easy and try not to do the same for someone else!