Folding KA when Ace is hit on flop?

My biggest money loser for me lately has been KA, I have put 20 dollars on party poker 3 times in a row, each time getting my 20 to around 60. I am playing 25/50 cent blinds

On each occasion I have got KA, raised 3 times the blind, so to $1.50, and have had 1 caller.

The flop looked safe, like A,4,7

They Raised to around pot size, I re raised around double, they put me all in, now should this be were I should detect they have better then me? Well I sort of did, but still played, only for them to have 4,4 and beat me.

Sorry for the bad example and not providing proper stats, anyways after this I told myself "ok you should now be able to know when someone has flopped 3 of a kind and should be able to fold next time"

Problem is 2 times in a row almost the exact same thing happened, I had KA, hit either the K or A on flop, and ended up all in, I just can't fold it!!! Is this normal, or would most fold, how can I think about it more logically to get myself to fold here?