Lying

So I live with my aunts fiance and his mom. Yesterday morning he got up quite early.. and when I asked him where he was going he said he was going to my aunts friend and her husband.. just to drop off a present for the husband. Later that day he was still out so out of curiosity I just asked him where he was galavanting? Then he says still at their house but that he was rather going to stay the night and that he would be back today. But his mom told me that he was going to be staying with them night all along... so why tell me that his just going for the day when he knew all along he was going to stay over by them. Because he was actually at their holiday house which is an hour away from us. I'm more upset that he lied to me about staying over. He should of just been honest from the beginning