Goodness, wasn't expecting quite this response!
So, to answer the theme of questions & some more context;
He and I have a VERY strained parenting relationship which is way too complex to update here, but generally goes along a pattern of him wanting the kids more for a bit, then meeting someone new and refusing to have them as much and round and round we go. This current cycle was wanted the kids 50:50 Feb/mar time, I agreed to almost that much, then new gf on the scene suddenly he was withdrawing time with kids and now once he moves in with her (planned for sept) he is dropping his contact time to a day or two for 4 weekends then nothing for 4 weeks, then day or two for 4 weekends again.....
This is the 8th or 9th gf the kids have met in the last 2.5yrs, the 4th he has been going to move in with.
Kids are 9 & 6yrs.
After 3 months she took my 6yr old to her house without my ex for the morning while he was busy with the 9yr old. Neither child had been to her house before.
If (and based on history it's a big if) this relationship works then absolutely I want the kids to have a positive relationship with her, and no I don't want to stop them having fun times.
He broke his ankle today, they had plans already for tomorrow but obvs he can't go. And yes it is his time to have the kids.
I think perhaps I have different standards and level of respect for him (and the kids) than he does for me. Maybe that's why this grates so much. I wouldn't have dreamed of allowing this with my partner after such a short time, and even if I had I would have let him know. Not asked permission, but certainly been open to hearing his opinion. And btw he was kept right up front with my situation with my new partner, even before the kids met him, before they stayed at his (with me) and offered the opportunity to meet him.