The entire point of Terra's "love" arch isn't love in the sense of a man and a woman. Rather it is Terra's own sense of abandonment as a child from her parents, meaning she was able to develop a complete sense of being fulfilled (we generally get our parenting skills from our own parents). When she had to look after the orphans she was able to experience that feeling which had been missing since she lost her parents through the children. Thusly Terra's story isn't about her and Locke, it's about herself attempting to remember a sense of loving in the world, which she does through the children.
On the other hand we have Celes, whom obviously draws parallels with Rachel, Locke's lost love. Locke himself obviously feels the need to help out both Terra and Celes because in them he sees the life that Rachel was denied, and such strives to continue that. However he becomes closer to Celes primarily due to the amount of time they spend together. It's also made quite obvious that Locke has feelings besides friendship for Celes (the opera scene), and oppose to Terra, whom he never expresses anything beyond friendship for.
Taking this into account, it's obvious that out of the two, Celes is the more prime candidate for a coupling than Terra could be. However during the game Locke and Celes never outright express anything that may indicate that they are an item, so any such theories are just that, theory and speculation. I don't think it's unlikely, but considering that Locke has strong feelings for Rachel even after her death, and Celes' distraught past, I can't see them falling into each others arms directly after the last battle.
Originally Posted by Maxx Power
