Is it true that an ex-friend can be a spouse but ex spouse can be an enemy?

Not necesarily, but scopes are there. It depends on the relationship you maintained. Enemity may form up as a follow up of those memories. Thank you.

I think generally it could be true. However, it all depends on the consequences of the divorce. Is it a third party case? Or both of them realised that they are some differences and would like to have mutual divorce and still stays as friends. If it is mutual divorce for pursuing their happiness, I believe they can still be good friends. Ex-friend can definite be a spouse, why not?