Money is a huge issue, but it isn't only about cash, it what the cash represents: Self-value (what he believes he's worth), perceived value (by the world, by a superior, by his family, by his family of origin), security (for himself, for his family), flexibility (lifestyle, providing for his family), achievement (self and in the eyes of others) and future considerations (college for kids, retirement, weddings, vacations). Yes, women also work and contribute to these items ... but most men will see this as their job.
How she can help: Stay active in the finances. Pay the bills — all the bills — together, regardless of who makes what paycheck. A joint effort means that success/challenges are addressed by both of you, and the stress is then shared. And let him know you're proud of him. It sounds like such a small thing, but your pride in him will mean a lot.