There's TL;DR down if you don't feel like reading the whole thing.

I've been with this girl for 9 months. Happy relationship, strong trust base, lots of thrill, she is attached, I maintain a very good frame. Sex is awesome, we fck hard every time. I keep her chasing a bit, some tease here and there. A bit more arguing the last 2 months tho.
The problem is my girlfriend was feeling lonely on the side of friendships, she was struggling to maintain friends who take interest in her, which I understood and let her a bit more loose to go out.

Anyways, she recently started going out with a particular girl, who I know very well and approves me. Thing is this girl(name her "C") has been in a relationship for a bit over 2 years and is not happy with her relationship, she has some serious problems in that. So, in my opinion, that's why she's VERY active with her friends- going out very often, visiting each others houses, they drink etc. Other girls of that particular company are single, or at least most of them.
My gf started going out with these girls, they are beautiful and high-status, which I am not afraid of, I've dated one of them.
Thing is, I feel like gf uses every single oppurtunity to go out with them, whenever they invite her and
we can only see eachother on Fridays, Saturdays and Sundays and these girls usually go out during the weekend. She still wants to see me but it's different.
This is becoming an increasing burden for me. I can end it and I know it will hurt me initially and I'll recover but I don't want to lose such a person, she's definately a keeper. I'm confused because she shares her future plans with me in them all the time.

I was getting back in town this Friday night and I thought we'd meet. We heard eachother on the phone at around 21:00, I was at that moment walking to a bar to see my friends and I thought she'd come too. We hear eachother and she says she'll think about coming- no pressure. She called, saying she'll stay home and wait for me so we see eachother later. Also says that she doesn't want to go to a bar that night, shares with me that she was invited by these girls to a "Girls night" on Saturday and wants to go. She texts me, asking when will I be done. She sent 2 texts and I called her because I knew something was up. She said she was going to C's house and wants me to call her when I'm done. I go pretty mad but I contained myself, I said I'll eventually call her because we might go to a disco, which was apperantly a problem with her. -In my head, she wanted to stay home that night just so she can go out the other night and not spend 2 nights at bars. She got mad at me and I acted passive, not very caring etc.
She sent an angry text to which I didn't reply. I went no contact, no hear from her,aswell, today (Saturday), she apperantly went out with the girls because of the photos in facebook which she's trying to annoy me with but that won't make me react in any way.

How do I get back from this? Tomorow is the last day I'll be in town and we might not hear/see each other, I'll probably go NC the whole week i'm not in town, aswell.
Are we going through different pages of our lives and need to split? I am struggling because we don't get to see eachother and spend time together like before and this affects me in a way that I get more distant and I start thinking about starting to cheat on her, because there are other girls I can fuck.

I want to share this with her but I don't want to go AFC mode and be controlling, because I have never been "that guy".

tl;dr
-gf feels lonely on the side of friendships the past months, recently starts going out with high-status, near-her-age female friends
-we can only see each other on weekends and she tends to go out with them more during that time, which leaves me a bit unhappy- I don't want to spend ALL the time with her by any means but I feel a bit neglected
-I feel like she uses every oppurtunity to get with them and go out
-most of them are single or in complicated and unhappy relationships or go out constantly
-I won't show but I start feeling insecure about our relationship and came on here to ask for advice

Sorry Shadzzz,

Sounds like she’s not ready to settle down.

Her friends are single and going out and having fun. She wants to do the same.
If her friends were getting married then she would be looking to get married and
settle down.

Your course of action. Break up with her. Start preparing yourself mentally that when the time is right. You can say something to affect…you know your friends seem real important to you and I encourage you to go with them and have fun. I’m looking for
A real serious relationship and settle down. So when you want that let me know maybe
We can get together again in the future. Leave on a high note. (She’ll probably come
Back in the future. Unfortunately, for her. You sounds like a great guy and will probably be with a better girl.

Your other course of action is to continue to fight with her and try to get her to change.
If you follow that path she will lose all respect for your beta behavior, break up with you and may never return.

It’s a tough spot. Wish you the best.
PM if would like more.

Agree here^

Also, you've left out details. I figured I'd check your posts for your age, then realized that you've posted about this girl before. This relationship was far from "great" and problem free. You got advice to dump in July and you said you did. Give complete details or you'll just get shitty advice.

Forget about what you think's going on with her for a moment. You've clearly stated that you feel "neglected" and "insecure". The unmet needs are intimacy (connection) and security; two needs are enmeshed in one another.

Keep in mind that "neglect" IS NOT a feeling, but rather an evaluation of what you believe the other person is doing TO you (and it may be true, or it may not be). I am imagining you're feeling on-edge, frustrated, and sad from all that's been going on lately. The feelings of not having your connection and security needs met. It is your responsibility, not hers, to have those needs met. What I mean by this is that if you are chronically looking for things outside of yourself to fulfil those needs, you'll be co-dependent, not inter-dependent.

So, what are you supposed to do with this information? As yourself what is it that you need to feel that your connection and safety needs are met? Once that's done, how might it involve the other person (in a gift-giving way)? So, for example "lately we've been seeing each other a lot less and I feel sad about that because I really value are connection (need), would you be willing to help me fulfil that need by scheduling some time together?" for example.

Sitting on here and asking guys what they think is going on with a girl they do not even know, and a relationship to which they won't understand anywhere near as much as you will help get you anywhere near having an authentic relationship with your partner.

Couldn't say it better