This is a bit spoiler-y, so I’ll hide things for folks who don’t want to know.
For a player following the “good” route and not aligning with the queen at the end of the story, you can be in a relationship with any or all of your companions at the end, and encounter at least three of their love scenes in a single playthrough. Pursuing multiple romance routes will eventually lead to a moment where your companion acknowledges this and asks you whether you’d like to fully commit to them (which will end the other romances), end the romance, or embrace polyamory and continue multiple romances at once with consent.
On the other hand, if you pursue the queen’s route, you can play out all the romance paths through their love scenes, but once you’ve made your allegiances to the queen clear at the end of the story, things get a lot more complicated. The queen is not the type to share, and your companions will not all take kindly to someone who sided with the queen. That said, betraying someone you were in a romance with and ending up on opposite sides of the war certainly lends itself to drama!