My girlfriend's best friend (29F) is boycotting our relationship and I need (29M) to know how to act in these cases, has anyone experienced something similar?

Hello to all,

My girlfriend's best friend broke up with her boyfriend and started partying constantly and became a bit paranoid about men, with themes like we're all the same, we're all liars, etc... So my partner since the beginning of this year has joined her going out partying constantly, I understand that she can go out and have a good time is normal but I think I can count on the fingers of one hand how many Saturdays we have seen each other or how many dates we have had.

Basically what brings me to write this post is that this christmas for some reason that she has never done before now she has decided that she is going to celebrate the new year and christmas partying with her new group of friends which consists of a bunch of guys who want to f*ck her (I'm not stupid) and her best friend who wants to f*ck them all.

Writing this I realise that I'm pretty stupid but it's fine (I guess), I don't have money for a psychologist and I suppose getting it off my chest and seeing if anyone is going through the same thing or has gone through it and can give me advice can be positive.

Thank you all very much and have a Merry Christmas.

UPDATE: I didn't think there were so many comments honestly, I'm reading them all and I've seen that maybe I should add more info.

We have been together for 5 years and in all this time this is the first time we are not gonna celebrate Christmas and New Year's together, I have always been the one who has gone to his house with his family.

About Saturdays: to say only Saturdays would be an understatement because she has spent the whole year in concerts and festivals (apart from nightclubs) so I could almost say that it has been the weekends that I count on my hand.

About talking to her: I've been telling her for a year that I want time for us but I want to make the old plans we used to make for dinner, movies, drinks, etc... but now she's only interested in going to the places her friend knows because the owners are her friends and they invite them to everything and they are ‘friends’ with the DJ of the place. I know the dj's girlfriend and she hates my gf and her friend because she's starting to live the same life as me if anyone is interested, so I wouldn't be scared if the 3 of us ended up single.

About her best friend: She told her boyfriend that she wanted to go out for a while, she slept with him for a month and when the boyfriend realised he left her for good and is now in another relationship. I've also seen comments that when her friend finds a guy she's interested in she'll leave her aside, and this actually happened a few months ago when she started to want to spend more time with me but it seems that this relationship only lasted a couple of weeks.

And a bit about me: I consider that I have given her everything, I have always let her do what she wants, hang out with whoever she wants and spend time as she wants, I have always respected her, I have made an effort to make plans that I didn't like so that she would feel supported by me I have tried to get along with her family and friends, and I spent the first 3 years supporting her because her mother had cancer and passed away in 2022. I don't care if anyone thinks I'm insecure or whatever they want to think. She has been the love of my life since we met at the age of 7 and I hope she understands that the decision will be like a shot in the heart. And to comment that she came from a very toxic relationship where they controlled everything, her outings, the friends she could have and all that shit, sometimes I think that I am paying the bill for her previous boyfriend.

SORRY FOR SUCH A LONG POST.