A friend of my bf's keeps inviting my bf to go travelling with him.

Ok, guys. Here is the story. My bf of 1 year has a friend who is working at the airport. About two weeks ago, This friend invited my bf to go travelling with him. And he could offer my bf free flight tickets. Just two of them. I asked my bf that if they were going to live in a same hotel room. He said yes. I told him that i was not comfortable with it. We had a argument about it and eventually my bf refused his invitation. And this guy texted my bf to invite my bf to go traveling to another city again in this morning. He said he didnt go traveling after my bf refused him. My bf asked me if he could go again. I was kinda mad. I told him that i 200% trust him, but i didnt really trust his friend. And I actually asked my bf if we could travel to the same city before . He said no, its a very boring city. Now he wants to go there with his friend. And this friend is having open relationship with his partner. Reddits, please give me some advices. I am confused. Thank you very much for stopping by and read my post.