I hate when people bring rejection back to me

I once confessed to this guy that I like him and turns out he didn't feel the same way and ofc I'm fine with that because it would be weird if I made a whole deal about it, like bruh. Anyways, my friend likes him and he likes her back and she came up to and said "hey, uhm I was wondering if you allowed me yk if he asked me out, would you be fine with that?" and hell yeah I would because no hard feelings all good, but I hate that people ask me, just do it!!!! It makes me feel weird when I realize that they rejected me and then went for my friend weird to think about it like that so I don't like when its brought up but when she said it me I was like "dude don't you worry, go for it" it's just mad awkward. And she's one of my closest friends so her asking me was cool but I hate that that's a thing and girl code is you can't date your friend's ex's or can't go for the guy that rejected them and whatever, like not a big deal. There was one point where I dated this guy for almost a year and we were like serious and committed relationship but then so much happened that we broke up, and one of my friend went and dated him without asking which thank god she didn't and all my other friends yelled at her for not even asking me and I had to tell them that I was so glad she didn't ask me. It's just like cool, go for it, idrc.