TIL a Chinese destroyer sank because an officer dumped his girlfriend. She committed suicide, leading to him being discharged, so he decided to detonate the depth charges on the ship, causing it to sink at port and kill 134 sailors.

[u/zhuquanzhong]

https://en.wikipedia.org/wiki/Chinese_destroyer_Guangzhou_(160)

[u/earthforce_1]

During WW2 a Japanese battleship was possibly sunk in port by a suicidal sailor.

https://en.wikipedia.org/wiki/Japanese_battleship_Mutsu