Aarmau
Aphmau used to write about them being together when she was younger but has forced herself to stop.
Garrence
Garroth sort of improvs little tunes to sing whenever they're doing something together about Laurence and then forgets about them 5 seconds later.
Melinda
They don't really write about one another but they write cute little notes to each other instead.
Travlyn
Katelyn wouldn't dare admit it but she's written plays with her boyfriend in mind, whether he's the lead role or not. She writes songs that he would be able to sing, and creates roles she knows he can act well.
Vylante
When Vylad's traveling some place he likes to write things about Dante or things that they did together to avoid homesickness. That used to not bother him before, but now he has Dante, who he probably wouldn't see for a month.
ZaneChan
Zane writes songs about Nana (spoiler alert for that one oneshot I wrote LOL) and refuses to tell her. Nana is his muse. For now, the songs are secret..