It is pretty much universally accepted that people change, so if you want to screw up your marriage, expect that your partner won’t. Chances are, you will change yourself as the years go on and the relationship grows so you must be sure to hold yourself to completely different standards than the ones you hold your partner to. That kind of imbalance is the perfect kindling to set your marriage ablaze. When your partner decides to make a major career change or alter the way they feel about something, feel free to not support them because that’s not what you signed up for. Unconditional is not really as unconditional as many people think, and your expectation should be that your partner always stays the same as the person they were when you married them.
You can also screw up your marriage by treating your marriage like a time capsule. Even though the world around you and your partner is constantly changing and growing, you should expect that your marriage will stay the same as it has always been. By doing this, you can easily become complacent with how things are, even if they are not great or even good. No matter how lackluster your relationship becomes, don’t try to make anything better because that would be inconsistent with maintaining the status quo. Even if by putting your heads together you and your partner could improve the relationship and grow as a couple and as individuals, don’t.
When expecting that things won’t change, be resistant when things actually do change. There might come a point where your partner is offered their dream job in another state. To screw up your marriage, do not support your partner and make sure they know that it is more important to you that things stay the same than their happiness and growth. When you sense your partner starting to change, avoid taking steps to help you remember why you wanted to be with them in the first place. If you do that, you might realize that who they are fundamentally is much more important to you than whatever changes they are going through, and you can’t have that if you want to screw up your marriage.