A woman's happiness is VERY precious.
When I interview guys on this topic, they often say that what got them attracted to their girlfriend is her smile and radiance.
It is the fact that she looked happy, fun and outgoing.
That's a trait you DON'T want your girlfriend to lose! Believe me!
That's what brings joy to your relationship and makes it fun to be with her.
The moment you kill that, you destroy what you care for the most.
You need to manage your jealousy without destroying these qualities in her.
As a life partner, your job is to protect her freedom and happiness, not to destroy them!
So, how do you manage that specific tricky challenge?
You trust her and tell her what the TRUE boundary is.
The true boundary is: "Don't get intimate with another man - If you do, I'm out"
That's usually the deal breaker in relationships.
95% of couples agree with this subtle and often unspoken agreement.
The other 5% of couples will have an open relationship or some higher degree of sexual freedom.
Listen, when she's happy and even flirty, what bothers you is not so much what happens there, it is the potential of what COULD follow up.
Guys get jealous because they IMAGINE what COULD happen next.
Of course if you see her flirting with another guy, it might bother you a bit.
But what really gets to you is if they establish a connection that can lead to something else.
She needs to know what your EXACT boundary is:
"No intimacy with another man"
Once she knows, give her space and trust her!