[ealgeone]

That’s right. If you are forced into a divorce, you can discuss it with a priest and make a confession if needed, and then you are in the same position as you were before, as long as you don’t remarry. If you want to remarry some time in the future and your ex-wife is still living, then you need to get an annulment before you can receive communion, unless you and your new wife agree to live chastely.

Where in Scripture is the "annulment" provision?

Living chastely doesn't constitute a marriage??

It's only a marriage if they have sexual relations?

What if someone looks upon someone else with lust? Adultery?

Even then, if you slip up without previous intent, you can confess your sin. But true confession requires that you INTEND to do as promised.

[Cicero]

Annulment is different from divorce. It means that the marriage was never real in the first place. Since that may be difficult to prove, it requires a decree of annulment from Church authorities.

Most obviously, there can be an annulment if one of the couple was already married, and their spouse was still living. So the second marriage never really took place.

There could also be an annulment if there was a SERIOUS misrepresentation by one of the spouses—for instance if one of them was gay or transgendered and neglected to tell the other beforehand.

Sexual relations in an ordinary marriage are a natural part of marriage, and are not unchaste. But they would be unchaste if one of the couple was divorced and remarried. Then the Church requires them to avoid sexual relations until the first marriage has been annulled.

I think most Catholics know all this, although this have gotten more confused in recent years when liberal priests or bishops have gotten involved.