One night I and 4-5 other friends celebrated the end of our exams, so we went out for a few drinks. As we start on a alcohol fuelled debate on who of our friends I (the only single one) would be best suitable for.
ive been close friends with a guy and a girl who have been dating for a few years now. They have had their ups and downs, but it seems that they are going strong.

After one of our friends told a joke about that I would not be a logical choice for anyone, the girl reached over to me and gave me a hug trying to comfort me, as she pulled away her hand rubbed and squeezed gently on my inner thigh, which sent shivers up my spine (in a good way)
After that night she has been flirting with me quite a lot. Shes not the most gorgeous girl but theres something about her that makes her attractive. I keep thinking about her, if i should do something about it, but i dont want to ruin their relationship. what should i do?