She began seeing him. It was just for coffees at first. Every time, she told herself it was innocent. All she was doing was seeing him, drinking coffee, and indulging in nothing more than the delicious filling sensation their time together left her with. Yes, there was sexual desire, but no sex. She knew she was using him as a patch. And she always told her husband where she was going and with whom. What harm was she doing, really? Better to be a bit with him and mostly with her husband, than not with her husband at all. Or better than being with her husband, but hating him for not measuring up. She needed that little bit extra. It satisfied her. It completed the list. What could be the harm in that? She figured she was safe. She figured it would be OK. Except, of course, it wasn't.

The more she saw of her two-box bloke, the more she wanted. She realised a mere pencil mark would not do – she needed more than just a stopgap. This new man had exactly what she was looking for and she couldn't deny herself the satisfaction any longer. Why should she? She thought. You shouldn't settle for less than perfect. Eight out of ten wasn't good enough. She began to recalculate. Did her husband really measure up? Perhaps he fell shorter of the mark than she initially thought. And perhaps the new man had more to offer than she had let herself see. "We're always told to reevaluate our jobs, why aren't we encouraged to reevaluate our relationships," she asked.

"When you're not happy, you write a list. If it doesn't stack up, you make a decision. Is it wrong to expect 100 per cent from everything?" It's probably the most natural thing in the world, I replied. We want the best. We crave perfection. We wish everything could be just the way we desire. Except the beauty of life lies in imperfection – having it all is not only impossible, it's ugly. "I don't think you should leave your husband because he doesn't tick all the boxes," I said. "But I do think you should strive to make your lives together the best they can be."

She didn't seem satisfied with my response. I thought about it. Was I right? Is it wrong to want it all, and expect to get it? I've written a lot about great expectations, and the problem of unrealistic goals. I've also written about the scourge of settling – when people cop out, and live with crap as a consequence. In the end, it has to be about balance, surely. Somewhere between everything, and nothing, is just right. Determining what's just right, for you, is key. Just before Christmas, my girlfriend came back to me. She had a confession to make. She had determined she was unhappy in her relationship to the point where she felt she had to leave it. She met two-box bloke for coffee with the intention of taking it further. She wanted to see whether he might, in fact, have more to offer.

But as her lips drew closer to his, and as she felt his breath on her neck, she thought about all the teary, late-night conversations she'd been having with her husband. The nights they'd spent lately, wrangling with the obvious truth of her unhappiness. She thought about his tenderness, his kindness, their history, and his understanding. All these thoughts were swimming through her head as she moved into this other man's embrace. At once, she was overcome with emotion – regret, sorrow, guilt, and, most importantly, love. Love for the man she realised gave her so much more than anyone else ever could. She pulled away. She looked at the other lover. She saw, for the first time, how little he really had. What had seemed like so much was actually nothing. It had seemed like more because it was missing, and all she could focus on was that small absence. She didn't see everything else was full. "I don't need all ten boxes ticked," she said. "Nine will do." Nine?

She laughed. Remembering how much she loved him had pleasant, physical consequences. I was happy for her. But I'm still not sure – if you've signed up to forever, will anything less than everything do?