I know we can’t actual make more time, but we can manage our time.
Have you noticed how regardless of how busy you are, if you really want to speak to someone, you will find time in your busy schedule? Others will do the same for you as well, won’t they?
If they don’t, I think you have to consider that you are not that important to them, and maybe they aren’t the kind of friend you thought, or wanted them to be.
If you care about someone, make sure you make time to be with them, talk to them and just as importantly listen to them.