You should try to get KK all in pre the vast majority of the time, including this situation. Most likely the problem in your last few sessions is variance, and not your inability to fold huge hands. Losing a stack AA v KK is not what is going to make or break your winrate. It hurts, especially if you are new to poker (not sure if you are, ive been playing online about 10 yrs and still stings a bit) but you can really mess up your winrate by over adjusting your game because of inevitable things like this. Just keep grindin and evaluating more routine spots.

Thank you for the encouragement, I will keep going!

Hello,

I agree with JRthekid32 on the way a set-up like AA vs KK has to be approached mentally. Just have a look at such an encounter on a nosebleed table (with run it twice, in addition!): I bet Trueteller surely laughed at it. ;-)

After a 2.5bb open raise, you should 3-bet to 9bb ($0.18).

After a PF 4-bet, easy 5-bet all-in with KK, and never mind if you are called by AA: of course, you will find AA in the range calling your 5-bet shove, but also KK, and even AK (remember AK blocks 3 AA combos and 3 KK combos, i.e. half of KK+ combos). And do not forget that a 5-bet shove with { KK+, AKs, AKo } can make a light 4-bet fold.