26f going on a holiday with my best friend 25m and his new (3 weeks) gf 23f

My best friend since we were 15 and I have been invited on a five day trip abroad. Also invited is his new girlfriend. They have been dating for three weeks.<br><br>I accepted the invite without knowing about his new gf. He has told me about her and that she is coming as well. We are all sharing an airbnb. <br><br>I don’t want to be the third wheel and ruin their time together but also don’t want to cancel and lose the money I already spent, nor ruin my friendship with this awkard situation. <br><br>What to do?