Would it be okay to ask my (22m) former coworker (22f) on a date considering her best friend rejected me half a year ago?

Recently I reconnected with my former colleagues at the party. I met the girl who rejected me and her best friend (let's call her Sasha) whom I haven't seen since February. It was a bit awkward, but I had a nice time with Sasha. Sasha knew that I liked her best friend and even suggested my candidacy to her saying that I'm smart and funny etc. I have always had a good time with Sasha. She was laughing at my jokes, rested her hand on mine and was respectful. She even invited me to her birthday even though we knew each other for about a month, but I think it was because I had a guy friend working with her for quite some time before I came to that job. She shared things with me, and once said that she wants to see me joyful. However, I liked her friend, and Sasha knew that. Girl whom I liked was giving me mixed signals that I mistook for attraction, but in the end she burst in anger and listed every negative aspect of mine right into my face. Funny thing we didn't even date and I haven't confessed or anything. I retreated and quit that job to focus on my uni. Half a year later I went to a party where I saw them again. As I mentioned, I had awkward moment with the girl whom I liked, but with Sasha, I felt comfortable and we chatted all evening, she hand fed me her salad which might indicate her being flirty (?). She told me about her personal things and shed a tear. That was a bit unexpected but it was okay. All in all that was nice seeing her.
Couple days ago I came to my friend's place of work so we could go to eat something, and Sasha was there. We would just talk and once again she gave me to try her tea from her cup (she must really think I have a good oral hygiene). After that we walked to the metro and she would be very talkative and engaged into convo. My friend told me she doesn't act that way with other guys or at least wasn't in the mood that whole day except when I came by. Would it be considered not creepy if I ask her on a date knowing that I already tried things with her best friend. Would it anyhow affect friendship between my friend and her? Should I even consider texting her, or was she just acting friendly?