Under-estimating non-marriage relationships

I work with quite a few people who simply live with their partners. From my perspective of my eternal marriage, this makes me sad. However, a thought came one night. I should not under-estimate those relationships. There are some important rules in mortal life:

1. Never under-estimate yourself.
2. Never under-estimate those you associate with, including your relationships with them.
3. The most important rule, never under-estimate the power of God to make worthwhile things permanent forever. If you choose that which cannot be made permanent, you are basing your life on puffs of smoke.

If you don't want to short-change your life, estimate highly. Find the strategies that multiply those life benefits that are worthwhile, and which make them permanent forever.