Independent, remote, and prone to addressing his inner audience rather than those in the real world, Squall is confined to introverted qualities. At best carefully neutral, and at worst ostensibly hostile, he shuns social interaction and embraces a solitary existence. His introvertism has its roots in both nature and experience, with perhaps the latter cementing the former and preventing any sort of extroverted behaviour from emerging.
As he and those from the orphanage begin to remember bits and pieces of their childhood, Squall learns that his tendency toward introvertism had been a childhood trait. Quistis remembers him as a distant playmate who only seemed interested in his "Sis Elle", or in fighting with Seifer (though this would feasibly not have taken place if it Seifer hadn't riled him on). From the beginning, Squall was one who kept mostly to himself, with few exceptions.
(Why do people depend
on each other? In the end, you're on your own.)
Perhaps Squall would have been coaxed out of his shell. Perhaps, as he grew older and more world-conscious, he would have embraced social relationships, instead of confining himself to a single relationship, or none at all. Perhaps he would have been more willing to disclose his thoughts and feelings to others, and rely on others as well as himself. Perhaps, in time, this was an attitude Ellone herself could have inscribed in him.
But Ellone's role in shaping his person would garner quite a different attitude, one that she would come to regret and blame herself for. Her sudden disappearance from his life, unexplained and unfathomable, would force him to embrace a solitary path of self-imposed exclusion. He would spend hours awaiting her return—in the dark, even in the cold and rain—and discover that he was indeed alone, and the experience would embed in him a sense of desololation when it came to trust in other people, and he would come to trust himself and no one else—it had been proven, after all, that the one you loved the most could betray you and leave you in confusion and hurt.
Heh heh heh. Quistis was right. You do have a hard time expressing your feelings.
The people he surprises himself in becoming close to express concern over his inability to communicate his thoughts. Rinoa, Quistis, and even the headmaster of Balamb Garden himself take note of this problem. Squall denies to himself that it is a problem; he is, after all, not the least bit interested in sharing his thoughts and feelings with anyone, and he can't imagine why anyone would be interested in the first place.
Eventually, and to even greater surprise, he discovers that his lack of trust in others, the void that would be filled with solid relationships, is indeed harming him. In spite of himself, he wants to place trust in others, and he knows he needs to.
But after being inwardly-inclined for so long, and having the natural disinclination to express his innermost thoughts and feelings, makes the transition from devout loner to someone just a bit more social difficult. Squall fails to see the importance in revealing what's on his mind to others, particularly when he can see nothing consequential coming from it. This speaks of a lack of understanding on his part. It is entirely reasonable that he would not recognise the importance of confiding in others, of listening to others and of sharing himself with others, for it was a lesson he'd missed learning.
At the gentle coaxing of his new friends and provoked by their insistence and sincerety, Squall finds himself in a struggle with his experiential and natural introvertism—a struggle that leads him into a new era of his life, both as an individual and in his newly developed relationships.