Regularly-scheduled campaigns are difficult to maintain. Couples spit; people drop out. Life gets complicated; there are children, jobs, sickness and seasonal activities (summer with kids, holidays,etc). Sometimes games just burn out, which I've somehow managed to do with two campaigns at the same time.
Online games are easier to maintain: someone else is keeping the server's running and patching the client software and usually writing all the 'story' which you and your friends use as a backdrop for your own stories. You (generally) don't have to travel anywhere, just be at your computer or console on time.
Question is: how does one reboot, recover and restart? The quest continues.