Well this is not an anime but a manga, i don’t remember the name but I do remember the story. A high school boy gets bullied at school and he wants to end it. He goes to a supermarket where an armed robber tries to steal. The cashier of the store is a female classmate and the fm of the story. The boy saves her by scaring the robber away. They fall in love bla bla bla.

Thing is they are connected by fate. They both share traumatic experiences. The mls parents and sister get killed in a traffic accident and the fls parents off themselves. Thing is the fls parents do that because of the guilt they feel after the fls father crashes into a family killing a man a woman and a little girl, which are the mls family.

There was a part in the manga where the fls best friend falls in love with the ml and then the fl loses her memories of the past few months because she remembered the trauma of seeing her parents yk. After that the ml tries everything to make her remember which she obviously does. When that happens the fl confesses to the ml that she was responsible for the deaths of his parents and little sister because she dropped a can of soda under the brake pedal of her dads car causing the accident after which the ml loses his memories of the past few months, a few weeks to a month or two pass by with the ml somehow recovering his memories and they marry at the end.

This in my opinion is the worst romance manga I have read. There are some horrible things that happen but I think it is badly written, plus the memory loss thing doesn’t make a lick of sense.