Jack here =D,
Im hoping its not gonna be a 3-some or something.. =|
All jokes aside, I believe that They have to be friends.
If its anything, i think it would be.
But who knows. ^_^
Edit: Actually just a thought, i believe that Maybe Terra is Jealous of Aqua because of ven/Aqua friendship.
Editedit: Also, Terra is a Loner, where not everyone hangs out with
But he finally understands friendship through being with The others! =D
I can see this but I could see Ven being jealous of Aqua admiring Terra and being worried for her.
Remember back to the trailers, she was the one who denied that Terra was submerging into darkness to Maleficent so she may look up to him as a role model.