Responses
She doesnt want her son to be taken? She won't have any control on her life? She can't make her own decision for her son? She doen't want her son to live such a strict life? She fear on the fact that ppl wont accept her and instead the lead male may just marry someone else and take his son?
I could go on with reasons why she hides it...

Why don't you just say it?
I was wondering why can't she just tell him everything.. she loves him... her son needs a father... her son wanted to have a complete family The father wants them..