New boyfriend????

Ok, well here is the scoop. I started dating a guy three weeks ago. I have met his family. He talks about marriage and brings up the subject for the most part. I am 20 and he is 23. Before we met he had planned to go on a vacation with a female friend in her 30's. He asked if it was ok and I said yes because she is in her 30's and seems more like a friend. She also invited a great deal of other people to go on this trip and my boyfriend is the only one that has decided to go. Tonight on the phone he asked me if it was okay again and I said that it was fine because there was not anything their. He said it was platonic and that there was not anything there. He also said that if she had not been married twice and was a Christain that he would totally be with her. He is with me and if he wanted to be with her he would be. But I still feel really odd about this. I need advice Please!!!