Again, TOF is a reverse harem.
(A reverse harem is the opposite of a harem, wherein a harem is directed towards men with women courting the main hero. In a reverse harem, it focuses on a heroine who is being courted by men, usually seven or more. -google)
Meaning...
Nea x Primo
Nea x Dos
Nea x Third
Nea x Quartus
Nea x Mayo
Nea x Haru
There is no canon ship in the story as of now. Some people might find this uncomfortable, so read at your own risk.
Thank you!