The correct answer to this open question is the following.
Jonas' dialogue and demeanor in each interaction suggest that his character is changing because both dialogues are completely different. When he speaks with the Giver, Jonas has a more mature conversation about tough topics regarding love, relationships. He seems to be vulnerable when confessing these things with the Giver.
The reader can realize that Jonas is having a deeper connection with the Giver when he told him that he wishes the Giver could be a family member, like a grandfather. This shows the reader that Jonas' character is changing.
On the other hand, when Jonas speaks with his parents, the situation is completely different. No warm or interesting conversations. Just rigid and formal conversations that are not interesting at all. Jonas ends up lying to his parents and he moves on with other things.