My wife is in a friendship group like yours and they all chat via WhatsApp, share pics, stories and arrange regular meet ups. There’s one girl in the group that generally cancels last minute and rarely responds to the messages. It miffs my wife no end and now when this girl does respond or cancels, no-one responds to her or says sorry she can’t make it. My wife is better friends with a smaller contingent within that group and often meets them on the side - I know they’re all slightly insulted and offended by the one that rarely responds - in reality this girl is having a pretty rough time and isn’t coping so well so it feels a bit harsh but she doesn’t help herself by being aloof and constantly cancelling with breezy excuses.
She could fix it though by turning up and being the person they all used to like. I know they’d all want to see her and would soon forget being slighted.
In general I think long term friendships can feel like a support network but if you draw on them too much without giving back and the give/take balance gets out of whack then you will lose that group support.. the love you get from friends is not unconditional and forever.
Re Ibiza I think you have to let that one go. Decide if you really want to be friends with these girls and if so, make the effort to be the good friend you used to be, get the balance back by making effort to turn up and be happy and take real interest in them and their lives for the first few meet ups. Apologise and build bridges and you’ll find the love coming back to you I’m sure. If you feel you don’t have the time or energy to do that then you know you have to let the whole thing go and focus your energy on other relationships. Good luck