Anakin Skywalker (a.k.a. Darth Vader) is the yandere for his wife Padmé.
He, along with his mother, were slaves on Tattooine. When Padmé (in disguise) visited the planet, she befriended young Anakin. He was able to join her and Obi-Wan when Qui-Gon is able to haggle Anakin's freedom with his owner. Years went by and he became Obi-Wan's apprentice. He was placed in charge of guarding Padmé, which leads to his feelings for her growing stronger.
Anakin is obsessed and possessive of Padmé. He doesn't like seeing her around other men, Obi-Wan in particular. His transformation into Darth Vader was a result of him fearing that he would lose her and their unborn children. He was also influenced by Sidius's promise that he could save her by joining him. This led to him thinking that he and Padmé could shape the galaxy however they wanted. However, her shocked response caused him to believe that Obi-Wan corrupted her and nearly strangled her with the Force.