I think you two have a good start! I’ve tried to find the middle ground between names for you. From his list, my favorite is [name_f]Cora[/name_f]; from yours, [name_f]Lydia[/name_f] and [name_f]Ivy[/name_f].
[name_f]Briar[/name_f]: For him, there’s the length, the rhythm, and the prominent “r” sounds. For you, there is the uniqueness (it is #718 in the top 1000), the fact that it’s a nature name like [name_f]Ivy[/name_f] and [name_f]Isla[/name_f], and that gently vintage, similar to [name_f]Lydia[/name_f] and [name_f]Adeline[/name_f]
[name_f]Cordelia[/name_f]: Strikes me as the perfect balance between [name_f]Cora[/name_f] and [name_u]Delaney[/name_u]. It has the quirk of both, and the starting sound of [name_f]Cora[/name_f] plus the “del” of [name_u]Delaney[/name_u]. It’s longer, and far less popular, than [name_f]Cora[/name_f].
[name_f]Colette[/name_f]: For him, there is the “Co” of [name_f]Cora[/name_f] plus the spunky and liveliness of [name_f]Freya[/name_f] and [name_u]Piper[/name_u]. For you, there is the relatively lesser popularity, the double “l”/double letter I’ve noticed in many of your names, and syllables that pop.
[name_f]Iris[/name_f]: If he wasn’t liking [name_f]Ivy[/name_f] or [name_f]Isla[/name_f], perhaps “I” flower name [name_f]Iris[/name_f] will win him over? It has that great “r” sound, and is tailored like [name_f]Cora[/name_f].
[name_f]Penelope[/name_f]: When I saw [name_u]Piper[/name_u] and [name_f]Pippa[/name_f], I thought of this. [name_f]Penelope[/name_f] is just as regal and mythological as [name_f]Freya[/name_f], and it has the elegance and length of [name_f]Adeline[/name_f].
[name_f]Poppy[/name_f]: Or what about [name_f]Poppy[/name_f]? It is a double “p” flower name for you, but is spunky like [name_u]Harper[/name_u] and [name_u]Piper[/name_u].
[name_f]Harlow[/name_f]/Harlowe: For him, it is tailored, bold, and with that “Har-” sound from [name_u]Harper[/name_u]. It also has the long “o” of [name_f]Cora[/name_f]. For you, it is gentler and more unique that [name_u]Harper[/name_u], and has the “l” sound that is present in many of your favorites. [name_u]Marlowe[/name_u] is another option.
[name_f]Ariadne[/name_f]: Mythological like [name_f]Freya[/name_f], the “r” like virtually all of his favorites, but with the femininity and “A” of [name_f]Adeline[/name_f] and the distinctiveness of [name_u]Delaney[/name_u].
[name_f]Felicity[/name_f]: The sounds of [name_f]Freya[/name_f] and [name_u]Evelyn[/name_u], packaged in a less trendy, feminine, longer name.
[name_f]Lyra[/name_f]: So many of both of your favorite sounds in one short, elegant, beautiful name.
Best of luck with your decision, and I hope this was helpful!