I can give you my experience? Personally it was from being in relationships. As a teenager people would ask me who I liked and whatnot and I would just kind of pick the most average looking boy I saw and say him. I didn't feel anything for anyone so I convinced myself that was what having a crush was. Later I ended up getting into relationships whenever someone liked me; because I thought that I could grow a crush or make myself like them, I didn't really know anything else. You have no idea how long I spent on like wikihow googling "how to date someone" and "how to know when you like somebody" then try to replicate what the internet said. eventually Id just heavily distance myself and talk to the person I was dating like once a week because I was so "busy" when I was really just avoiding them.( whenever we would break up they would usually be broken up by it even though I made them dump me, but I was only even indifferent or relived. even when they would attempt to publicly embarrass me)The moment I realized I was aroace was my first time making out with a boy. It was terrible. I was just there thinking "am I supposed to enjoy this? it's so awful and awkward" from there a couple months later I found out about the ace spectrum then was questioning for like a year, I still do (even though Its painstaking obvious I don't feel romantic attraction like my friends do). I hope this helped!