1. First, when Blair read Serena the letter she wrote her when she left for boarding school without any explanation:
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2. When Eric came out to Serena:
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3. When Dan and Serena realized they needed to finally break up, and they shared one last kiss in the elevator:
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4. When Blair couldn't accept her breakup with Nate:
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5. When Chuck considered suicide because he thought his father was dead:
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6. When Blair told Jenny nobody loves her:
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7. When Nate turned his dad in for using drugs:
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8. When Chuck lied and told Blair he didn't love her back:
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9. When Blair had a miscarriage:
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10. When Blair told Chuck she was done fighting for him:
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11. When Eric told Blair he had tried to kill himself:
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12. When Serena saw Dan move on quickly after their breakup:
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13. When Nate stayed in the hospital all night with Serena after she was in a car accident:
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14. When Chuck slept with Jenny because he thought Blair didn't love him anymore:
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15. When Serena and Blair's prom didn't go as planned, so they ended the night together, just the two of them:
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16. When Blair told Chuck she never thought he would hurt her like this:
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17. When Serena broke up with Nate:
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18. And finally, when Blair told Serena there was nothing she could ever do to make her let go of their friendship:
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