<human>: Hey,

**at first some background information:**

My gf[24] and me[22] are dating for about 6 months, we live ~ 150km apart.
We met through a mutual friend. We mostly see each other on weekends.

Before our relationship, she was together with a good friend [20] of her, which didn't work out and she broke up with him after 3 months.
He is her best friend and the only friend left which she can see without driving 30 min.

**Now the problem:**

The first three months she didn't see her ex very often. But after some time that started to change. 

At first they started texting and calling each other, mainly because he had some family/work problems. 
In the last 2 months they started to see each other more often, meet for sports or talking, etc. And recently they see each other each day, except when I stay at her place or vice versa.

Since then I became really jealous and started getting a bad mood if she mentioned him or meets him. To me it looks like she exchanges me for him when we can't see each other.

We've talked about it a couple of times, but only if one of us was mad already. 
I don't want to forbid her meeting him, she doesn't want to stop meeting him.

For me it's not the fact that they meet, it's the frequency that really bugs me. 

I don't know what to do or say to her, because I want this relationship to work on a long term basis and the fact that I get a lousy mood  almost every evening is not really helping.

Can you summarize the given text in a few sentences?
<bot>: GF and me live ~ 150 km apart. When we're not around each other she meets very often with her ex. I get jealous & mad.