I guess it depends on what you mean - I interpret "even keel" to mean a constant state of balance to some degree. I don't think that's really possible for anyone but I do shoot for "equally yoked" meaning that when one is weaker/down/needy the other is up/stronger/filling in.
Those moments when we need to be able to rely on our partners come unexpectedly so to me "evenly yoked" means that I can trust in my partner enough to know that whenever/however that situation arises, he'll be there to whatever degree I need & that I will certainly offer the same support when the tables are turned.
We were NEVER evenly yoked while he was actively drinking & progressing in his alcoholism.