I think, after reading your last post, that you will be going with them unless, as you hope the holiday is booked. And not entirely their fault ...
If you had substituted they would get the hint that they were not invited with 'Sorry, we're off by ourselves this time, how about a weekend later in the year?'
I am just hoping that it is fully booked. Same substitution as the last one!
I said, More than once, 'if you want to go out for dinner on your own one night that would be fine with us'. They didn't want to.. Substitute with 'We're going out for dinner on our own tonight' and maybe 'Do you want to meet for drinks afterwards?' if you feel like it. As someone who doesn't read hints, I welcome, and am not at all offended by, straight speaking! They like your company. It seems your OH likes their company too, so be a bit more straightforward about how you feel and you all might enjoy your time together more.