May-December Love Brings Financial Issues

"They thought this was off the plate, and they were walking into retirement in a position where they could be financially independent," McGervey says. "But having a spouse who is much younger and has a family can change that picture quite a bit."

Life insurance and estate planning issues also get more complex.

A younger partner might face a hardship in the event an older breadwinner dies prematurely. In other cases, the earning power of the younger partner may be a lifeline for their older mate.

In a blended family, ensuring that post-death assets are properly distributed can be a source of tension.

"One of the spouses is usually the one who is bringing the majority of the assets to the table," McGervey says. "But even in the case where we have equal assets brought by each family member, there is still a lot of discussion around making sure the assets they brought to the table go to their lineal decedents rather than going to those of their spouses."

This becomes especially tricky if there's a remarriage after the passing of a partner.

McGervey suggests the establishment of a qualified terminable interest property trust.

"This type of trust would make income available to the spouse to cover their health, education and maintenance support," he says of QTIPs. "There may also be some provisions for distributions that are permitted. They can be very comfortable and, upon his or her death, the remainder of the trust -- and most have the ability to retain their principal value -- then goes to the designated descendants."