MARAUDERS HEADCANON #2
Remus and Sirius were always very close, so when they started dating nobody suspected anything of the extra hugs and long "good nights".
Until one day, after a especially hard moon, Remus comes into the common room and just sits next to his boyfriend and kisses him full on the mouth.
Not many people were shocked, but James made a scandal, complaining about why they hadn't told HIM.
Peter and Lily were just whispering to each other "I knew it".