Best friend problems?

A couple of days ago, my friend invited me to the movies with him, so i asked him if i could bring my girlfriend too. He gladly excepted because he told me the other day that he really wanted to meet her. Shes really attractive and really nice, so the two got along really well. After the movie, my friend was happy for me and said that i was lucky to have her. The next day, he tried to make me jealous by saying that he met a really hot girl, and he also said that i should be jealous of him because the girl that he met was so much better than my girlfriend. This maid me say some things to my friend, and he said some back to me. And after all of that it turns out that he lied about ever going to the beach and he never met anyone. The point is, why did he do this? And please dont say to find him a girlfriend because i wont, he needs to find his own special person. Also, my second question is how do me and my girfriend sound together like a couple, my name is lance and her name is amber? Thanks, and please provide a good detailed answer.