Well, in some fanfictions, the moment when Minato sacrifices himself to save the village while Kushina is already dead is extremely emotional. It shows his selflessness and also the love he has for the village and his family. Also, the flashbacks in some stories about their early days together, like when they trained together as young ninjas and slowly fell in love, are really sweet and emotional.
One memorable moment was when Minato saved Kushina from being kidnapped. It showed his determination to protect her. Another was their wedding, which was a celebration of their love in the Hidden Leaf Village.
The moment when Kushina first realized she had feelings for Minato was crucial. It was during a long and difficult mission. Minato was injured, but he still managed to keep a positive attitude and protect Kushina. His selflessness made Kushina see him in a new light. Also, when Minato proposed to Kushina in front of the whole village, it was a big moment. It showed their love was not only between them but also something that the whole village could celebrate.
One key moment was when Minato saved Kushina from danger. It made Kushina see him in a new light. Another was when they shared their first real conversation and got to know each other's dreams and fears.
The moment when Minato told Kushina that he would always protect her, no matter what, was really touching. Also, when Kushina was about to give birth and Minato was by her side, ready to face any danger to keep their family safe. It showed their strong bond and the depth of their love.
In fanfiction, a very memorable moment could be when Kushina is feeling down about her situation as an outsider in Konoha, and Minato comforts her with warm words and a loving embrace. It shows the depth of their relationship. Also, their wedding day is surely a highlight. The whole village celebrating their union, with Minato looking at Kushina with so much love in his eyes. And when Kushina discovers she is pregnant and they share the happy news together, it's a moment full of joy and anticipation.
One key moment could be when Minato saves Kushina from danger. For example, when Kushina is attacked by enemy ninjas during a mission, Minato arrives just in time, his speed and power impressing Kushina. Another moment is when they share their first kiss. It might happen during a beautiful sunset on the outskirts of the village, with the warm light making the moment even more special.
On a more personal level, they could face internal guilt. As Naruto grows up and achieves great things on his own despite their neglect, Minato and Kushina may realize what they've missed out on. This realization could cause them a great deal of internal turmoil and regret for not being there for their son when he needed them.
Minato would probably be very proud. He might notice Naruto's use of his own jutsu and be impressed by how Naruto has developed his skills. Kushina would be more emotional, maybe crying at the sight of Naruto growing up so well.
It might be due to jealousy. If Minato was getting more attention or praise in the village for his achievements while Kushina felt overlooked, that could create resentment. Say, Minato was constantly being hailed as a hero for his speed and battle tactics, and Kushina, who also had great power, felt like she was in his shadow.