* CrowningMomentOfHeartwarming: Two examples.
** "But love, he said, love was a fragile blossom; love was a delicate crystal; love was an unstable reaction with a half-life of about eight months. Bullshit, I said, and accused him of wearing cultural blinders; thirty centuries of prewar society taught that love was one thing that could last to the grave and beyond ''and if he had been born instead of hatched he would know that without being told!"''
** [[spoiler: "I never found anybody else and I don't want anybody else. I don't care whether you're ninety years old or thirty. If I can't be your lover, I'll be your nurse."]]
* EndingFatigue: Used to good effect, as Haldeman sets up the story such that the only way to end it is to force an ending. This reinforces the point that the war has gone on so long that people no longer have any idea why they're fighting or what they hope to accomplish.
* UnfortunateImplications: Halderman's depiction of homosexuality in ''The Forever War'' is quite infamous for the amount of criticism it's attracted.
* WhatDoYouMeanItsNotPolitical: Conscript soldier in a war with no objectives against ill-defined enemy for government that doesn't give a rat's ass about winning or losing, who comes home to a world he doesn't recognize and that doesn't really want him. And the war [[spoiler: [[TheWarOfEarthlyAggression is itself based on false pretenses and started by asshole generals]].]] [[UsefulNotes/TheVietnamWar Nope, no allegory here.]]
* TheWoobie: Mandella.
* ''Potter's father comments that the war is the reason why everything is so bad when they return after their first tour; "the very best fell to the Elite Conscription Act and wound up being cannon fodder."'' Yet the small size of the forces doing the actual fighting appears to contradict this. OK, so they need a large military industrial support network to fight a war in space. But surely a lot of that would still be based on Earth, unaffected by relativity and therefore still able to contribute to Earth's economy?