Main Characters:
* Finn Hudson: Finn starts with Quinn Fabray but ultimately ends up with Rachel Berry. He also has a brief relationship with Santana Lopez and explores his feelings for Kurt Hummel.
* Rachel Berry: Rachel's primary love interest is Finn, but she also has a complex relationship with Jesse St. James. She also has a brief fling with Brody Weston.
* Kurt Hummel: Kurt is mostly known for his relationship with Blaine Anderson, but he also has a brief but impactful relationship with Karofsky.
* Blaine Anderson: Blaine starts the series with a brief relationship with his boyfriend, David Karofsky. He eventually ends up with Kurt Hummel.
* Santana Lopez: Santana starts as a bully, but she develops a strong relationship with Brittany Pierce and eventually finds love with Brittany. She also has a brief relationship with Finn Hudson.
* Brittany Pierce: Brittany is known for her quirky personality and strong bond with Santana Lopez. Their relationship evolves from a close friendship to a loving romantic relationship.
Other Notable Relationships:
* Puck: Puck has several relationships throughout the series, including a brief fling with Quinn Fabray, a relationship with Lauren Zizes, and a relationship with Shelby Corcoran.
* Quinn Fabray: Quinn starts the series with Finn Hudson and also has a relationship with Puck.
* Tina Cohen-Chang: Tina has a few relationships, including Mike Chang and a brief relationship with Artie Abrams.
* Mike Chang: Mike has a relationship with Tina Cohen-Chang and also has a brief fling with Marley Rose.
* Artie Abrams: Artie has a relationship with Brittany Pierce and later a relationship with Tina Cohen-Chang.
* Mercedes Jones: Mercedes has relationships with Sam Evans and also a brief relationship with Shane.
It's important to note that some relationships were short-lived, some were more intense than others, and some characters experienced more than one romantic relationship. The series also explores the complexities of sexuality, identity, and love.
If you're interested in more specific information about particular relationships, you can ask about them individually, and I can give you a more detailed summary.