Conundrum

Have you ever been in a situation that makes you doubt your decision, even though when you look at the parties involved in the situation you know you are still right?

I am in one of those precarious situations right now.

Lets explain it this way... Party A is young... Party B is Party A's senior by almost a decade. Party A is in a position in it's life where the only things that matter are partying and making sure that their budget is managed well enough to include gas for the car to get to the parties and the ocassional meal as to not result in death due to starvation. However, party B is in a very different stage, children, relationships, full time jobs, bills to pay that do not include debts to the local deal, you know the regular adult domestic stuff. Now Party B is wise and also very sensitive... call it a bit isolated if you will. Party A has shoot off mouth syndrome that has no effects on anyone because Party A has yet to learn that there is reprecusions for everything in life. A says a series of things to B without thinking and inadvertantly hurts B feelings and makes B doubt decisions that have been made long before the conversation occurs. Since A still has blaitant disregard for everything other than partying and the occasional meal, how does B deal with A? How does B help A to understand that this is wrong and that A needs to start to consider the possible outcome of the hurtful words that spew from A's mouth all too frequently?
Does it help with the dilemma if A and B are related?
What about if A doesn't repsect B?
Just to add another loop in it A nd B are the same gender!

Help... any input would be greatly appreciated.