Been married 20 yrs, split up 18 x's,Do these signs have an influence on his unstable behavior?

The reason you two keep on splitting up is because he won't change his behavior.

The reason he won't change his behavior is because he knows you will take him back regardless.

Instability in the birth chart is shown by the aspects, not by the signs.

Aspects are certain distances, measured in degrees of arc, between any two planets in the chart. You look at aspects involved any of the 10 planets.

Planets represent inner needs, and some distances create inner harmony, while others create inner stress and tension. Obviously, a planet with mostly difficult aspects will show the negative side of the sign.

However, in the end we all have free will The chart is only an influence. The chart does not "make" us anything .. it is an influence and we either run with that influence, or we make choices and decisions and take charge of our life.

Your husband could have changed if he had the motivation and perhaps some techniques/suggestions. He has no motivation. If he has not changed by age 56, he's not likely to.

I just hope he didn't psychologically damage your children too badly.

It's quite possible that the "answer" could be in your chart. Rather than trying to figure out why he behaves the way he does and when he may or may not change, figure out why you have attracted and attached yourself to such a mate.

Does the drama thrill you? Are you intrigued by the uncomplimentary nature of your union? Would you be bored if the situation were so-called "stable" and uneventful?

Dig into your motivations a bit and see what you can bring to light about yourself. In my experience it's really very rare that one spouse wants the other to change. It's futile and deep down everyone knows this to be true. Very simply put, when YOU decide to not enable the situation, that's when YOU will have changed and the situation will respond accordingly.

Marriage is a choice, your beliefs are a choice, as such YOU have chosen the situation you find yourself in. It's easy to pass the blame and look for his faults while painting yourself as the the ever enduring forgiving wife. Look into why you picked that role, rather than trying to find proof that it has been forced on you... through some symbol in your astrology chart, or your religion, or your upbringing, or your husband.

It's possible it's time for him to "grow up" but it's perhaps time for you to be responsible for your choices and actions. Everything in your life, most especially your spouse and close loved ones, are a reflection of you.

What about his whole chart ? maybe you get a better answer.