No more comment,thank you

Sometimes ppl will ask me to listen to their stories and then ask for my opinion.I always give suggestions which I think are the most suitable,but not anymore.They can actually decide themselves, so why ask for my opinions?If I spent weeks to think a solution for them,and in the end nothing is taken,I felt like I am wasting my time.I don't know about others,but my time is somehow precious.I respect other ppl final decision,and i always think they know what are the thing they want,and this is what I want,no more comment,thank you.