For some people, saying, ‘I don’t spontaneously want sex as much, shall we start scheduling it?’ can be difficult. You’re acknowledging a change in your relationship (even if, as you said before, that could be a positive one). Why can that conversation feel so loaded?

The idea of initiating a plan for sex is so fraught. We’re all fragile and fearful of rejection, and it requires great vulnerability to say, ‘If we showed up for sex at three o’clock on Saturday, I’d be glad to be there. I’d put my body in the bed.’ To ask for that is to risk being turned down. And our identity is tied to our success as sexual people. Some heterosexual men, in particular, are taught to believe that the only way they can access love and be fully accepted is by putting their penis in a vagina. So if their partner says no, they’re not just saying no to sex, they’re saying no to their partner’s whole personhood. Sex itself is not a drive, but connection is, and we don’t grant men access to other channels for giving and receiving love. If a man in a heterosexual relationship can recognize that there are other ways he can give and receive love, that would take pressure off of sex. It wouldn’t be as much of an obligation for the woman, because she wouldn’t feel she was rejecting his entire humanity just by saying, ‘I’m too tired for sex.’ That has nothing to do with his humanity, she’s just exhausted.

What do you wish you’d known about sex and desire?

The neuroscience of pleasure. The simple way to think about it is if you’re in a sexy state of mind and your partner tickles you, it could feel good and lead to other things. But if that same person tickles you when you’re pissed off at them, you might want to punch them in the face. It’s the same sensation with the same partner, but your brain interprets it differently because the context is different. So in order to know what pleasure feels like in your body, it’s not just about saying, ‘Touch me here. Don’t touch me that way.’ It’s about creating a context that allows your brain to interpret a sensation – any sensation – as pleasurable.

During our conversation, I was reminded of this quote by the poet Rainer Maria Rilke: ‘Once the realization is accepted that even between the closest human beings infinite distances continue to exist, a wonderful living side by side can grow up, if they succeed in loving the distance between them which makes it possible for each to see the other whole and against a wide sky.’ Like Rilke, Susan helped me to understand that distance in a relationship is not a threat; it is a door to a more rewarding connection.

If someone is self-reflecting and self-regulating, what are the next steps?

I reteach communication (because at that point it’s probably got a bit mean) and negotiation, which allows a couple to see that in most situations, apart from ultimate deal-breakers (for example whether or not you want kids), you can both get what you want in a relationship. Then it’s also the ability to take responsibility for your own feelings. To keep yourself together. To be mature and balanced. To not just think, right, you’re going to have to put up with every single flicker of emotion I have.

I’m not saying we should be able to do this a hundred per cent of the time; we’re not robots. It’s about getting into the habit of thinking, I can feel myself getting angry. It’s fine to have this feeling, and it’s important, because it’s telling me something. But what should I do with the feeling: do I snap at my partner? Do I walk away and slam the door? Do I lash out verbally? And crucially, do I lose the sense of ‘we’ rather than ‘I’? Or, instead, can that person think about how both parties are viewing the situation, and say, ‘Look, I’m feeling angry at the moment. I need to find a way to calm down and then I can listen to you, I can reflect on myself, I can start taking responsibility and we can have a conversation which includes both of us’?

Susan pointed out a useful contradiction in love: if you lose a sense of yourself as an individual it can damage a relationship, but if you can’t accept that your needs and wants are not the only story, then it will be difficult to understand your partner’s perspective. That’s why it’s useful to think as both ‘I’ and ‘we’, to live together and apart, to trust the distance between you as individuals and learn to share your life with another person too.

All of this, I think, comes back to a word I never used to associate with love: responsibility. Maybe I’d never considered it before because I’d been too focused on being loved, rather than loving someone, and what that might require. Responsibility is at the root of many of the valuable lessons Susan shared: be as kind to your partner as you would to a stranger. Don’t rely on them to meet all your needs (or to make you happy). See arguments in context. Don’t expect them to put up with every flicker of emotion that you feel. Sift through your own feelings first.

My earlier attempts at love had been a falling – a rushing, crazy, forceful feeling that took control of me, overshadowed everything else. I was not answerable to it, or accountable to it; I was lost in its drama. So at first I did not understand what the psychoanalyst Erich Fromm meant when he said that love is ‘a “standing in”, not a “falling for” ’. But this, I think, is the process Susan describes: standing in love. Developing the emotional maturity it takes to remain steady, to hold your balance, to have control over your position. To give the person you love the gift of spaciousness. To not lean wholly on them, but to stand beside them.

What do you think the couples who are able to move past an affair have in common?

There are many things that make them succeed. But, in the reverse, I can tell you one ingredient that you know will prevent the success: when the person who betrayed and lied and deceived has very little empathy. That is a real giveaway of something that can’t heal. And the same thing is true on the other end: if the person who was betrayed has no ability to engage with the curiosity to understand what the affair was about. When the only way they can think about the affair was how it hurt them, it’s a challenging dynamic. The curiosity of the betrayed is secondary, but it’s equally important. Basically, to succeed you need each person to bring a degree of empathy and interest and deep desire to understand about the experience of the other.