people cheat in the name of spiritual connections. There are very few people who actually connect without any materialistic needs.
The world doesn't understand the ultimate reason to connect. It always boils down to needs. Also, there has to be a difference or else people who trust their partners fully, often end up being cheated of their dignity and self-esteem.
Financial obligations is just one reason for people to unite. There are many such reasons because of which the marriages don't survive in today's times.
Because the couples are not spiritually connected to each other, they go their separate ways after a while. :)