If a woman dies while her husband is displeased with her, does that prevent her from entering Paradise, given that her first husband died while he was pleased with her, and she is relying on the hadith: "Any woman who dies while her husband is pleased with her will enter Paradise"?

Have a good opinion of Allah that He will provide you with a righteous husband. Do not worry about your deceased husband's approval, as the decisive factor is the last husband you are with. If marriage becomes easy for you, be keen on pleasing your new husband and obeying him in what is good. If he becomes angry with you, strive to appease him, as the Messenger of Allah, peace and be upon him, said: "Shall I not inform you about your women from the people of Paradise? The affectionate, the fertile, the one who returns to her husband; if she harms or is harmed, she comes and takes her husband's hand and says, 'By Allah, I shall not taste sleep until you are pleased.'" If he dies while he is angry with you without any fault on your part, then there is no blame on you. If it was due to your fault, then supplicate for him frequently. Hasten to marry if it becomes easy for you, as studying does not contradict it.