Tara is Roy's former fiance, but she passes away with cancer before they get married. Roy, being devestated, rejects to ever see a women again like he saw Tara, which is why (present time) he is still single or messing around like a confused teenager.
The image takes place 10 years back, where Tara's last words are "Shauna, take care of your brother- Roy, I love you"
Shauna (present time) is Jimbo's girlfriend while Roy is a 42 year old lost cause.
Shauna (c) Matt Groening
Tara (c) Me
Roy (c) Me