Met a FWB chick through Tinder. I lost virginity to her (at 27) and she was very cool and understanding and honestly comfortable to have sex with. Overall we both told each other that we are FWBs and that if one side catches feelings we should tell instantly.
She's also kinda "almost bi" as she says as she will make out with her female friends when drunk and often "joked" about introducing me to some.
Also last time we met we talked about girls and my success with them (it got better, got approached and exchanged Insta with an actual 10/10 chick, but after one date it seems like it didn't really work out) and she literally told me that we need to go to a club and we will find a chick for me and i joked that maybe some threesome will happen and she was like "why not".

Question is - where is the red flag? Like, there is a red lamp constantly lighting up at the back of my head that something is not right or will blow in my face. Anyone with more experience can pitch in? Should i just go into it and let it happen or dip out?