The cheerful partner may be cooking a cake for their visiting nephew or whistling a tune while they rearrange the kitchen.

They may be making plans for the weekend or discussing what fun it will be to see an old school friend again soon,

or they may be expressing unusual optimism about their professional future and financial prospects.

Despite our love for them, something about the situation may suddenly grate with us.

Within a short time, we may find ourselves saying something unusually harsh or critical.

We may point out a flaw with their school friend: they tell very boring anecdotes and they can be pretty snobbish.

We may take exception to the arrangement of the cupboards.

We find fault with that cake.

We bring up an aspect of their work that we know our partner finds dispiriting.

We complain that they haven't properly considered the roadworks when planning the weekend.

We do everything to try to induce a mood of anxiety, friction and misery.

On the surface, it looks as if we're simply monsters.

But if we dig a little deeper, a more understandable, though no less regrettable, picture may emerge.

We are acting in this way because our partner's buoyant and breezy mood can come across as a forbidding barrier to communication.

We fear that their current happiness could prevent them from knowing the shame or melancholy, worry or loneliness that presently possess us.

We are trying to shatter their spirits because we are afraid of being lonely.

We don't make this argument explicitly to ourselves, but a dark instinct in our minds experiences their upbeat mood as a warning that the uncheery parts of ourselves must now be unwelcome.

And so we make a crude, wholly immature but psychologically comprehensible assumption that we will never be properly known and loved until our partner can feel as sad and frustrated as we do,

a recalibration of mood that we put into motion with malicious determination.

But of course, the truth is quite the contrary.

We may succeed in making our partner upset but we almost certainly won't thereby secure the imagined benefits of their gloom.

They won't, once their mood has been spoilt, emerge with any greater appetite for listening to our messages of distress or for cradling us indulgently in their consoling arms.

They will just be furious.

The better move , if only we could manage it , would be to confess to, rather than act out, our impulses.

We would learn to get to know the mechanisms of our immaturity with unfrightened curiosity while making every effort to protect others from its effects.

We would admit to our partner that we had been seized by an ugly fear about the consequences of their happiness, would laughingly reveal how much we would ideally love to cause a stink,

and would firmly pledge that we naturally aren't about to.

We would all the while remind ourselves that every cheerful person has been sad, and that the buoyant among us have by far the best chances of keeping afloat those who remain emotionally at sea.

The spoiling argument is a wholly paradoxical plea for love that leaves one party ever further from the tenderness and shared insight they crave.

Knowing to spot the phenomenon should lead us, when we are the ones baking or whistling a tune, to remember that the person attempting to ruin our mood isn't perhaps just a monster, though they are a bit of that too.

They are, childishly but sincerely, worried that our happiness may come at their expense, and they are, through their remorseless negativity, in a garbled and maddening way, begging us for reassurance.