Let me lay some heavy advice on you. The US Federal Government knows way more about you and your habits than you do. During my trip to SE Asia with my Filipina fiance'; we traveled to may places. It was her first time out of the Phills. After our travels, We parted ways and took different flights to our respective homes.
When I returned, the CBP asked me what countries I traveled to. I was exhausted and I could not remember everything. I just told him "I can't remember them all, you will just have to look it up". He smiled and said, "Oh you knew I already had the answer to the question as soon as you stepped off the plane?" I said, "are you kidding me, I should ask you if my fiance made it home safely". He said "hold on." Click click on the keyboard.
"Yup, she made it to Cebu safely"
I was not surprised in the least. I said, "thanks for letting me know."
He said, "no problem and welcome home"
So, yes they ARE going to check your travel records. They know everything. The US Treasury trades information real time with CBP. As soon as you hit the purchase button on the American
Airlines website, CBP knows all about your plans. How did the CBP know who my fiance was? Easy, I purchased the plane tickets in the Phills with my US credit card with me and my fiances name. I purchased the ticket for her to get to Cebu, under her name. I should have asked him if she took a p!$$ on the plane too, he probably knew the answer.
CBP uses algos (AI). So while your fiance may not have technically broken the law, she violated the spirit of the law. The visa is not for her to live in the USA with an American boyfriend, playing house for months at a time. An education visa is for formal education and not sex education. Also, even if you are lucky to get a K1 visa, the CBP is the sole arbitrator whether she gets in or not. If they are having a bad day, you are $h!t out of luck.
So if a CBP was upset with you or your fiance, take heed. Say "I'm sorry, may I have another. It will not happen again.". They hold your happiness in their hands. I agree with the others here. She needs to stay away for a very long time to "clear the deck". Most of us wait over a year for our fiance's to get here. You need to stand in line like the rest of us.
Good luck. Please do not play with fire.