Ya...it's not healthy to do the...well if you go out on a date every Wed, I need to go out every Wed on a date or it's screwed up. My husband used to go bowling every Wed night, so my default date night with my boyfriend was Wed. Bowling is over so he keeps himself distracted if he doesn't want to be home alone feeling aimless. When I wasn't dating anybody and my husband had weekly or more dates, it was my job to keep myself busy with hobbies. Your husband perhaps needs to find a nice regular hobby that ideally you can coordinate your date nights with your bf on.
We do have a default "no more than 2 dates a week with somebody" that is open to negotiation if we get in a position where we want to see somebody more than that, but as it stands, we feel it's our job to make sure we aren't infringing on the others free time. It's a last resort to pull the "I'm bored and lonely so you shouldn't be having fun" card. If we let that be dependent on if the other was in a relationship or not, it wouldn't be that fair to the people we dated.
Happiness will never come to those who fail to appreciate what they already have.