[name_f]Nova[/name_f]
[name_f]Ivy[/name_f]
[name_f]Celia[/name_f]
[name_f]Astrid[/name_f]
[name_f]Prima[/name_f]
[name_f]Acacia[/name_f]
Possibly also [name_u]Aspen[/name_u], [name_f]Arbor[/name_f], [name_f]Olive[/name_f] and [name_u]Grey[/name_u], but [name_f]Olive[/name_f] seems a little too sweet and the other three I prefer for boys.
Some I don’t like next to [name_f]Gaia[/name_f] at all, like [name_f]Lila[/name_f]/[name_f]Evie[/name_f]/[name_f]Poppy[/name_f]/[name_f]Isla[/name_f]/[name_u]Skye[/name_u] (too insubstantial), [name_f]Briar[/name_f] (very similar in sound, although I love [name_f]Briar[/name_f]!), [name_u]Sutton[/name_u]/[name_u]Blair[/name_u]/[name_u]Hadley[/name_u] (way too modern in style)
I like [name_f]Catalina[/name_f], [name_f]Penelope[/name_f], [name_f]Margaret[/name_f] and [name_f]Seraphina[/name_f] as well, but they feel way too long and elaborate next to [name_f]Gaia[/name_f].
[name_u]Love[/name_u] some of @truenature’s suggestions, particularly [name_f]Phaedra[/name_f], [name_f]Freya[/name_f], [name_f]Eleni[/name_f], [name_f]Junia[/name_f], [name_f]Luna[/name_f], [name_f]Noor[/name_f] and [name_f]Priya[/name_f].
Would add [name_f]Carys[/name_f], [name_f]Nona[/name_f], [name_f]Clio[/name_f], [name_f]Audra[/name_f], [name_u]Hero[/name_u], [name_f]Lyra[/name_f], [name_f]Persis[/name_f], [name_f]Zelda[/name_f], [name_f]Margo[/name_f], [name_u]Vesper[/name_u], [name_f]Delphi[/name_f], [name_f]Eleri[/name_f], [name_f]Ffion[/name_f], [name_f]Ishbel[/name_f], [name_f]Liora[/name_f], [name_u]Marian[/name_u], [name_f]Meissa[/name_f], [name_f]Oriane[/name_f], [name_f]Parisa[/name_f], [name_f]Phoebe[/name_f], [name_f]Olwen[/name_f], [name_f]Rosa[/name_f] and [name_f]Thisbe[/name_f]