McLaren switched their engine supply from Mercedes to Honda in 2015 but have endured a tumultuous three years since.
The British team have not finished on the podium at all since the move and after yet another disastrous season including 13 retirements, McLaren terminated the contract early and will use Renault from next year.
However, executive director Brown is keen to keep Honda close in the future in case they improve their F1 operation.
“Ultimately we knew we were in trouble in testing in Barcelona, and we worked really hard for six months to try and find some solutions that give us some confidence that we would be much more competitive in 2018,” Brown told Sky Sports.
“Ultimately after trying many different things, many different ways, all of which were reported on, we felt that we couldn’t get there.
“Three years is a long time in Formula 1 so we needed to change directions to get our team back on top.
“The decision we made is one we believe is the right one for McLaren.
“We are grateful to Honda. They’re a great company, with great people, and the relationship was always strong.
“The relationship still is strong. Wouldn’t rule out racing with them again, wish them the best but we needed to make some tough decisions to do what’s in our best interest.
“They’re a great company, we’ve won a few world championships with them, they know what they’re doing.
“For a variety of reasons, kind of didn’t get it right this time.
“But we’ve maintained a good relationship, so definitely never say never in this sport.”