The Bible says when King Saul found out that his daughter Michal was in love with Saul’s rival David, he was pleased. Saul had been afraid of David, but this gave him hope. Now he would have an opportunity to try to get David killed in the process of proving he was worthy to marry the princess.
But a few verses later, it says when Saul found out that Michal was in love with David, it just made him more afraid of David.
Maybe Saul found out that she loved David, and then he completely forgot what he had learned. Then he found out again, and had a different reaction the second time. That would mean he would have to be forgetting about things that were significant to him awfully quickly. But it wouldn’t be the first time (or the last time) Saul inexplicably seemed to quickly forget something important.
For instance, he apparently forgot that David had already earned the right to marry the king’s daughter when he killed Goliath. Saul’s son Jonathan also has some baffling episodes of forgetfulness. It must run in the family.