Perhaps the devil is in the details? What's the difference between this situation and when my partner tells a person he's dating that he doesn't have the time to develop a relationship into the "partner" stage, and that they'll need to grab the time they can, around each others' schedules?
He's not telling her that M1 or I are limiting him, but in reality, his schedules with us (and work, and his daughter) will limit his time to develop any new relationships. In his particular case, it didn't work, but they tried and both had enough schedule constraints that it wasn't going to be feasible.
BoH may not need to tell anyone new that "my BF has said that weekends are his" but instead say "weekends are unavailable". Will that be enough for someone new? Maybe not. But it's honest, and it's not passing blame to her BF. And if it becomes "not enough" then maybe BoH and her BF can negotiate?
Mono, in an LTR with Chops
Chops (previously known as 'P'):
partner and best friend. Poly. In LTRs with me and Xena, and dating Noa.
Xena (previously known as M1):
My metamour, Poly. Also in an LTR with Chops. Dating Noa and some others.
Noa (previously AG):
Dating Chops and Xena (individually).
My navel-gazing blog thread:
A Mono's Journey Into Poly-Land (or, "Aw hell, there's no road map?!")