I've been casually seeing one girl for the past 3 weeks. I made it clear to her that I'm not after a relationship, but she has continued raising the relationship topic every now and then. I met another awesome girl 3 days ago, and I've slept with her twice. The first girl is asking me to meet her again tomorrow night. If I do meet her, should I let her know that I'm seeing someone else as well? Will this hurt her?