I’ve killed every garden I’ve neglected, which is all of them: bring me a struggling houseplant and watch it die. But bring me a struggling marriage and I will sometimes encourage it back to life. Other times, when the conditions are right, by which I mean when something is wrong, I will kill it. Intentionally. Or, in more professional language, I will advise it to end. Not every plant gets to flower. Not every marriage should be saved.I have come to realise that care and attention, the fundamentals that keep both plants and relationships alive, are absent from many marriages that survive anyway. I call them cactus marriages: alive, but I couldn’t tell you how.Jess* and Pete* came to see me: they had raised their kids and always turned up for their jobs – at least with work someone writes down what is required of you. Neglect, it turns out, takes longer to kill a marriage than it does a garden. When couples remember how to be loving, the cactus thrives, and sometimes it even flowers, which surprises everyone, including me.But not every struggling marriage I see is a neglected cactus. Sometimes the soil has gone sour. And sometimes the roots have been severed, intentionally, and no water reaches a severed root. From across the room, neglect and its harder cousins, soured and severed, look the same: quiet and unhappy. Up close, the difference is everything.Sour soil looks like Diane* and Thomas*, married more than 30 years, whose fighting had become a script neither could stop performing. She raised her voice. He corrected her grammar. She brought up his breath. A trade economy where no one wins. There was no innocent party in that room.