I agree with the above; normally I say you should always try to honor a commitment, but given the situation - it's well in advance, the band doesn't exactly have a great relationship with the venue, and the band does not want to keep playing there - I think in this case you might as well call it a day and cancel.
It's not a big deal when it's this far in advance, and it's by no means the only time a venue has had a cancellation. Bands are queueing to get gigs so it's not as if you're causing some massive problem for the venue. Just do it nicely and there won't be any hard feelings.
It's not a big deal when it's this far in advance, and it's by no means the only time a venue has had a cancellation. Bands are queueing to get gigs so it's not as if you're causing some massive problem for the venue. Just do it nicely and there won't be any hard feelings.