Definitely bizarre behavior. I never done a half-board charter so maybe its a little different. We normally do a full-board and we make it a point to take the crew out for at least one dinner a week, and maybe a lunch or two when possible, just to give the chef a day off. We also make a point of spending a fair amount of time ashore to give the crew some down time. We've NEVER had a crew assume they were invited on shore trips and meals out.

We hired a captain once on a "bare-boat" trip in Croatia. The deal there was we had to provide his meals. We usually had lunch aboard and he ate with us. BF and dinner were mostly ashore and occasionally he joined us, but most of the time he happily hung out with the friends he seemed to have in every town.

If you haven't already done so, adjust the gratuity for your odd crew.