Actually, The Makers Of Digimon Frontier Didn't Continue There Show When They Grew Older.. They More ON Focus of How Takuya And Zoe Fall In Love.. And To All Fans Of Takuya And Zoe: They Didn't Get Married At All..!!..
In Digimon Frontier it gives us a hint that Zoe and Takuya likes
each other but it doesnt show any hints that Zoe like Koji. So I
guess Zoe does NOT like like Koji I guess only Takuya.