It's often said there's a "third person" in most dysfunctional relationships. The presence of a football team, PlayStation or, in Princess Diana's case, Camilla Parker Bowles, can leave you feeling left out, forgotten, alienated and tired.
And it's much the same living with someone else's depression.
There's a sense of shame in complaining about your partner's mental illness. You aren't the one who is ill, sad and feeling hopeless, so you have no right to moan.
As someone who has never suffered personally from depression, but has been affected by friends', family members' and my boyfriend's struggles with what he refers to as the "dark cloud descending," I'm here to say that you have every right to feel you are carrying a burden.
People with depression and, as a result, low self worth, will often try to push you away. At their lowest ebb, they can feel not worthy of your love, time and efforts to pull them back from the abyss.
It takes strength, resolve, good friends and a fair few bottles of white Merlot to stand beside someone with depression, see through their illness to the person they can and want to be, and it takes patience to wait until they are brave enough to start taking the steps to get there.
But what can you do in the meantime? Here are the coping tactics I've developed to stop me stabbing my boyfriend in the chest when he has what I very flippantly like to refer to as, a nark on.
LEARN MORE ABOUT DEPRESSION
Podcasts discussing mental illness helped me a lot, in particular US xoJane colleague Sara Benincasa's Sex and Other Human Activities, where she and the treacle-voiced Southern hot pot Marcus Parks discussed their respective mental illness alongside things they like to do with their genitals.
It has been invaluable in helping me understand what people with anxiety and depression deal with on a daily basis, making me much more sensitive to the signs of depression and less likely to act out when I become victim to them.
Sara has now left the show (GET BACK TO PODCASTING WOMAN. MY RELATIONSHIP NEEDS YOU). But the archive is free on iTunes.
There are a hundred books on Amazon about the subject, but I would really recommend finding stories in the first person, rather than some sort of textbook or practical guide.
Speak to friends, family members and colleagues who suffer from depression. They can shed light on what your partner might be going through and help you decide whether it's something you want to deal with in the long term.
Depression is a recurring battle and it's better to accept it as part of who a person is than to fantasise that they will one day be 'fixed'.
Speak to trusted friends about your feelings, too. Just because it's not your illness doesn't mean you are being indiscreet talking about how it affects your life.
REMEMBER: IT'S NOT YOUR FAULT
Write this on a mirror, Post It or tattoo it across your flippin' tits if you have to, but someone else's moods, depression, sadness or anger are, if they suffer from mental illness, probably not your fault.
I'm not saying that if you have filled the Tivo box with each and every incarnation of the Kardashian franchise and he kicks off, you should respond with: “Darling, do you think maybe you're angry at yourself?” But if someone is depressed, a dark mood can occur for no good reason.
Stop asking what you did wrong. If you did do something, it's their responsibility to share it with you, not yours to drag it out of them.
GIVE HIM SPACE
The last thing anyone having a tough time wants is to be pestered or made to feel guilty for ruining a date-night. Trust me, I've tried enough times to turn the tides of sadness, you just end up making it worse.
Make sure your partner knows you are there if they want to talk, then occupy yourself elsewhere, maybe watching that Kardashians marathon, until the storm passes.
I may have used a lot of seemingly lazy weather metaphors here, but trying to cheer someone up by saying: “Please cheer up,” is much like trying to waft away rain clouds with a tea-towel, you'll just end up exhausted. You have to wait until the sun comes back out.
So -– over to you. Any ways you have found to deal with someone else's brain functions? Us depression widows need to stick together.
Tory stays chipper on Twitter at @ToryFrostWrites