Here is the hard part first: two Cancers together can create a house with no windows. Both of you retreat when hurt instead of saying what hurt you, and when neither person pushes to open the door, the silence just sits there, sometimes for days, calcifying into a grudge nobody named out loud. You share the same instinct to protect the soft parts of yourselves by going quiet, which means there is no one in the relationship whose job it is to break the standoff. You will both remember the offense with total clarity and neither will bring it up first. That is the real risk here, not drama, just a slow drift into unspoken resentment.
And yet when it works, it works because you are speaking the same emotional language without translation. You know what a sigh means. You know that a bad day requires soup left on the doorstep, not advice. Cardinal energy in both of you means you each want to be the one who initiates, who plans the anniversary dinner or decides where the relationship is headed, so you may find yourselves gently competing over who gets to take care of whom, which is a strange but very Cancer kind of argument to have.
The Moon governs you both, and moods will rise and fall together in ways that feel less like conflict and more like shared weather. You will remember every birthday, every small anniversary, every quiet thing the other person said in October. The tenderness is real. Just make sure someone is willing to knock on the door first.