He normally only wants ... is he different with me?

So everyone says that my bf nvr takes relationships seriously... that he just dates girls that will have with him. Well he knew before we started dating that I didn't want to have and he still wanted to date me. He and his last gf only dated for 3 weeks and they had twice... and we've been dating for 3 weeks and all we've done is kissed once. Is this a good sign or bad?