I came to Chiang Rai to buy coffee for a week. Eight years later, I still negotiate prices with the same cooperative, though now I'm also part of the family.

I'm Canadian, 39, and I work buying single-origin specialty coffee for a roastery in Vancouver, a job that takes me travelling several times a year to coffee-growing regions around the world. Chiang Rai entered my route eight years ago, when my company got interested in the high-altitude arabica grown in the mountains of Doi Chang and Doi Tung, near the Myanmar border.

My first trip was supposed to last a week: visiting several farms, cupping samples, negotiating prices for the next harvest with local cooperatives. One of those cooperatives was run, on the quality-control side, by a woman named Kaew.

Kaew was 34 at the time, trained in agronomy in Chiang Mai, and she was the person who decided, before any sample ever reached my hands, which lots were even worth cupping. We argued, that first week, over an entire lot she refused to certify as export quality even though I, with a palate trained more in cupping rooms than on real farms, found it perfectly acceptable.

She was right, not me. The lot had a fermentation defect that only showed up after a darker roast than the one I'd tried at the first cupping. I admitted it openly in front of her whole team, which, she told me later, wasn't something foreign buyers did very often.

I came back three months later for harvest season, officially to oversee the drying process for the lots we had bought. Unofficially, to see whether Kaew was still as confident as I remembered. She was.

We spent that entire season basically together, cupping samples every morning before the heat set in, riding up to farms only reachable by motorbike on roads that became impassable during rainy season. She taught me to tell, by smell before taste, well-processed coffee from mediocre coffee. I taught her, with less success, some business English she needed to negotiate directly with buyers like me without relying on a middleman.

One afternoon that second season, a sudden storm turned the road down the mountain into an impassable mudslide, and we got stranded at the cooperative's highest farm, no phone signal, with only the farm owner and his family for company. We ate rice and a chicken slaughtered that same afternoon, slept on mats on the main room floor, separated by a makeshift curtain the family hung without anyone asking them to, and spent a good part of the night talking in whispers so as not to wake anyone, about nothing in particular and everything at once. We came down the next morning, mud up to our knees, and neither of us pretended anymore that it was just work.

I asked her, at the end of that second season, whether she'd want the relationship to be more than buyer and supplier. She laughed and told me she'd spent months avoiding the question herself, because mixing business and something personal in a small cooperative, where everyone finds out everything, seemed complicated.

We complicated it anyway. Her family, who've farmed the area for generations, received me with the same practical caution Kaew used when assessing a coffee lot: no instant warmth, plenty of quiet observation before deciding whether I was serious or just another passing foreign buyer.

Eight years later, I still buy coffee from that same cooperative, though the price negotiations now are considerably less formal than at the start, given that the person across the table is also my wife. We split our time between Chiang Rai and Vancouver, though I spend more of it here than there every year. I still haven't won a single blind cupping against her, eight years of trying.