Lesbian?

I was at a pool and I noticed a fairly attractive girl. I asked for her name and after brief flirting she asked for my number and Snapchat. I’ve been texting and hanging out with her for about 2 weeks now. Recently she gave me her Instagram. However, After I went on her Instagram,I was surprised to she has a girlfriend and has been in a relationship with her for several months. Was she just being friendly and I’m missing the Mark here? Any advice would be greatly appreciated.

Edit: I meant to post this weeks ago.