It is also made clear in the game that Terra isn't looking for the same kind of love that others feel. Consider the following lines:Originally Posted by Smlee
TERRA (after her meeting with Edgar): I guess a normal girl would have found him dashing. But I’m hardly normal…
Ok, that might have been a bit of paraphrasing there, I don’t have a script on hand right now. She does say something VERY close to that though right after she first meets with Edgar. This line implies that while Terra is capable of acknowledging external beauty, she is unable to consider it in anything more than an objective state. This in itself is not simply a ‘lack of experience’ issue. Even Miranda in The Tempest feels sexual urges, despite growing to the age of 15 before ever seeing a male other than her father (‘cept Caliba, but you know…he’s Caliban!). It’s something deeper, perhaps a side effect of an Esper breading with a human, or maybe due to the many experiments that were performed on her while she under Kefka’s control.
It would have been logical to take Terra’s love issues and turn it into a relationship with another character, yet the game’s featured relationship is between Celes and Locke. Instead, Terra becomes the care taker of an orphanage, and explores love in that manner. This seems to be enough for her, and from this one can conclude that at the very least Terra has a diminished desire to enter into a sexual relationship.
So anyway, Terra is not the sort that would engage in premarital intercourse, and certainly not with Edgar.