Answer:
1. He didn't want to worry her because she already had a lot of problems.
2. This shows that they had a very good relationship and that they cared a lot about each other.
Step-by-step explanation:
Percy's mother had to marry a terrible and extremely violent man. She did this because his human aura had a disgusting smell and that would allow evil creatures to not smell Percy's divine scent and not try to kill him, but Percy doesn't know that and believes his mother already has too many problems and takes a very difficult life, so he decides not to worry about the strange things that happened to him.
This shows that both are very concerned about each other and sacrifice themselves in an attempt to make each other safe and happy.