I have some questions regarding obedience to ones parents.

1. Is obedience to ones parents unconditional if they are commanding something halal?

2. Say ones parents have such high expectations that it is realistically unreasonable for one to fulfill these expectations, yet they are disappointed and angry at their child for not fulfilling them (even if it may have been in his theoretical capacity to meet them). Has a sin been committed in this case?

3. Is it permissible to disobey ones parents in secret, if it has no chance of humiliating or displeasing them?

4. If ones parents command one to marry someone, is it obligatory to obey them or does the child have the right to say no? Conversely, if one has been ordered not to marry someone, is it obligatory to heed to this command?

5. As a man, is it still obligatory to heed their advice even if it may make them upset?

Please find answers to first three questions here in this answer by office if his eminence:

http://ijtihadnet.com/childrens-obligation-toward-their-parents-according-to-ayatollah-sistani/

Re 4, no it’s obligatory. Re not marrying someone it depends if it’s a girl or a boy, and the reasons for parents not allowing the marriage

5. Try as much as you can to make them understand. Do not disrespect them. But sometimes they will not accept and that’s the nature of human beings