Lots of good advice already here, but I'm going to add on.

my ltr

A lot of newbies throw this term around recklessly.

1) LTRs are measured in years. Anything shorter, and it's not an LTR yet. So how long have you two been together?

2) LTR does not necessarily mean exclusive. Are you two exclusive?

If you two haven't even discussed who is exclusive to whom, then you have no call to stop her. Go fuck other women.

visit a club

Like others have said already: girls' night being dinner or just hanging out at one of their pads is fine. But clubs, bars, and other meat markets? No. Even when they aren't consciously aware of it, the only reason to go to places like that is to bask in male attention. They can dance at one of their houses/apartments.

The prevailing opinion on this is to say something along the lines of "I don't commit to women who do that" or "do you think this is the behavior of a woman in a committed relationship?" and your delivery of this matters more than the actual words you say. If you sound clingy, needy, insecure, or like you're mateguarding, you will be damaging your position. If you have an air of "here's how it is, and what you do is up to you" then that's better.

Ideally, a commitment-minded woman wouldn't even entertain going to something like that while attached ("lead us not into temptation"), but here we are.

If you hadn't explained to her that those behaviors are not acceptable by your standards, you should now. And also expect an argument. That's why you should make your boundaries clear before a relationship even started.

If you do try to explain to her why girls night out is bad, try not to be emotional or go too far into explaining why. Just say this: "I think that's disrespectful towards your partner and I would never do this to you. If you still choose to go on with it, that's your choice, but I'll also have to think about this relationship". End it there and refrain from any argument. Leave if you need to.

Then it depends on how she reacts. Most often they'll still go with their friends and you can demote her to plate while you go on the search for another woman who doesn't need to go party to feel good about herself

Just tell her "my gf doesn't do that". No mateguarding.

From there, it's up to her what she does. If she act like she' single, you treat her like one.

I've been djing for 10+ years, clubs, bars, festivals..clubs especially are mating ground. And no, she won't go there to dance. Don't fall for these "don't you trust me" shit. She might not cheat, but the fact that she's putting herself out in that situation is telling, especially if her friend is a hoe.

Or you know, don't be the controlling guy and be open minded liberal cuck, then write novels here when you get cucked eventually.

Dump her straight away. Then go buy yourself some outdoor gear and some tinfoil. Build yourself a hut in the woods and form a tinfoil hat so that the government can't read your brain waves. Go full on MGTOW. The last thing you want is a partner that has fun right?

I suggest that you do some more work on your self esteem. Mateguarding isn't a successful practice if you want a girlfriend to admire you. The harder you tighten the reins, the harder she is going to pull away from them.

You are going to be that guy that she grows to resent. She will tell her friends about you and they will poke fun of you behind your back. They will talk about how insecure you are. How you pathetically need control. This will get in her head. Her friends have sway. You'll end up a cuck when she brach swings. Her friends will have a toast to you being gone when she ditches you.

You shouldn't be with a girl if you can't trust her to spend time alone with her friends.

Mateguarding is like putting a sign over your head saying "I'm insecure. Make me a cuck".

Explain to her in clear terms, in a calm, cool and controlled manner, why it bothers you and that you consider it unacceptable in the framework of your relationship.

Don't push back, get angry or raise your voice. Just say it in a "sky is blue manner".

Then mentally discount her and let her do her thing.

After she decides to go ahead, you can demote her to plate status or dump her if you can't handle being emotionally cold with her.

If she does as you like, then good.

I'm old, but same advice years ago as today.

Going out for a drink, dinner with the girls is fine.

going out with them to a "club", no. doesn't matter if all the girls are married or in LTR's or not.

Girls go to clubs , to "be seen", by men. To get "approached" by men, to "dance" with men and flirted with.

simple as that.

The dance club would be out for me. I'd tell her that's not cool with me.

If she pushes back or goes, that's all I need to know.

She's gonna go get railed by Chad. Why else would she do that?

You need to communicate to her that this isn't acceptable.

If she shouts and stomps her foot and calls you controlling, then you have your answer about how to proceed.

Women go to clubs for male attention...... that's why these places they go "just to dance" are never ever female-only.

So what this tells me is that you clearly didn't vet this girl for at least a year before getting into a serious LTR with her. I mean, you can still try to remedy this and draw a line with her but like someone else here said before me, EXPECT A FIGHT. Not only from just her but from her friends/family as well.

Remember bro, this society doesn't like it when women love, respect, and admire their man. So not only is she going to resist being submissive in that sense but also her friends and family are going to urge her to push back behind the scenes as well, leading to either a quick or slow breakup.

Good luck G, see you on the other side.