So I was recently chatting to someone who I had not seen for sometime and wanted to encourage them to return to a club that I had often seen them at previously. I went out for coffee with them once, where I stated that I was already in a relationship and had a girlfriend.
It is clear that when I next texted this other person that they thought I was just trying to flirt with them, which I wasn't intending or trying to. I had a long discussion with my girlfriend about how this had been going and I made the decision to not contact this other person.
I recently went out on a date with my girlfriend and saw the other person there, and they asked if I and they were still on for meeting at lunch, at which point I said we were not and they left. At this point, I knew I had unintentionally led them on about my relationship status. My girlfriend encouraged me on the date to invite the other person back, but they said they were busy (so I ruined the friendship.)
I have since sent a lengthy apology, but they have not responded. I did not want to end the friendship. How can I mend the friendship with this person?