Why do girls and women give me dirty looks in public?

When I'm out in public, and see/ look at females I find attractive, when I make eye contact briefly, they give me a dirty look.

I've been told if I want to appear approachable, I should smile in a friendly way, but it doesn't work, it makes it worse as well as awkward.

I get the impression that females find me unattractive/ ugly/ and disgusted with the way I look.

Females never approach me, or even talk to me, and when I try to, they say 'I have a boyfriend', or make up an excuse just to get away from me all the time.

And I hate the way I look already, but this just makes me feel even worse about myself in genral...

So what can I be doing wrong?

I've lost weight (I was obese, weighing over 20 stone, not sure what that is in KG, but it was over 100kg).
I even got a new style with new clothes, to look more approachable, as well as look presentable and clean.
And my hygiene is good, never had a problem with it.
Why do girls and women give me dirty looks in public?
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