Health – Not sure if you were serious or not but it doesn’t sound like they’re having such major marriage problems that would require divorce or therapy c”v. Although seeking advise from rabbanim and other knowledgeable people is always a good idea, you seem to imply that their marriage is on the rocks. Every one has differences and arguments in a marriage (and this is a pretty typical one) – nothing wrong with that! Question is how to deal with it.
Trim – how about suggesting to her – without even mentioning her spending habit, that you think it’s a good idea to start a savings acct, or CD, etc. – give her a good excuse/reason (for the kid’s weddings, buy a house- whatever will work for her.) Decide together on a certain percentage or amount of what you earn each month will go into this acct. Then if you can afford and there’s still a few dollars left, if she really wants, let her buy something sometimes! It’s ok to OCCASIONALLY splurge on yourself (or spouse) as long as it’s in control. If there’s no extra, maybe she won’t feel the need to spend.