Is this a symptom?

Not sure where this should go... 

My husband (adhd-er) never wants to do anything that involves leaving the house.  I either give up, or I force him to do it and he's moody about it at first before eventually having fun.  I don't ask him to do things that he won't enjoy doing, unless it is an obligation that we cannot get out of (family responsibilities mostly), because i cannot deal with the way he behaves if he's bored, disinterested, etc.  I understand that his behavior when he's bored/disinterested is because of the ADHD, but is his hesitation to do anything outside of our house also a symptom? Recently he's been saying that he thinks it is, and he knows that once he's out somewhere he has fun 95% of the time, but it still has to almost get to the point of an argument before I can get him to go.  He will also agree to do something ahead of time, and then the day of, 10 minutes before we are supposed to leave he will flake out on it.  This has happened in situations from tailgating before a football game to going to my parent's to visit for the weekend.  I hate telling people that he'll be somewhere and then feel like I have to make excuses for him when he's not and I don't have the time to convince him.

So, symptom, or something else?