Tommy,
If the topic of marriage has come up, I'm assuming it's a serious relationship. Then if that's the case, your feelings need to be respected. It does not matter that SHE sees it as just some harmless fun; YOU don't see it that way. You have a problem with it, and if it's interfering with the way you feel about her, about the relationship, or about yourself, you have every right to feel the way you do. This is not about you wanting to restrict her. This is about your emotional well-being needing to be respected. And if she's insisting on going out without you - because nobody is going to tell her how to live her life - then she is completely diregarding your needs. The question then becomes: Do you want to live your life with someone who puts their
wants ahead of your
needs? It's not a hopeless situation, but she needs to be made to understand that this kind of disrespect is
unacceptable, and if she continues to not care about your feelings, it means she has chosen herself above her relationship with you. And you will leave.
We tend to preach that a lot here, to draw lines in the sand and follow through when someone crosses it. It comes across, to the unseasoned eye, as a bunch of homewreckers trying to break apart couples, some of whom have been togeter decades. And it's true, quite often someone will be advised to leave a relationship. However, we don't do it because we despise couplehood or marriage! Quite the contrary. Our reasoning is that life is much to short to not live right, and it's not right to allow yourself to be made to feel like less of a person by staying in a relationship that degrades you. Love others as you love yourself is a beautiful law to live by...but one thing people tend to forget is how to truly love themselves. And love isn't always gentle in its demands...even of one's self.
I would suggest taking some time to yourself to truly consider who you are, what you want, and what you need. Work on yourself and get centred. When you find your centre this way, it is very easy to feel when someone is disrespecting you as a person. And you will be much less apt to put up with it.
Don't know if this made any sense or not, Tommy, but that's my 2 cents anyway.
Welcome to the board.