The calculated wisdom of the 'first wife'

Extramarital affairs are not uncommon; it is unusual when every development of the affair is scrutinized by a billion plus onlookers.
When Chinese film and television star Wen Zhang was recently exposed for carrying on an illicit affair with another performer, both he and his actress wife, Ma Yili, were thrown into the maelstrom of public attention. Wen immediately apologized, and his wife, almost in lockstep, quickly accepted his apology, effectively taking the heat off him.
Any public-relations expert could have drafted Wen's statement of apology, which basically tested his sincerity. It is the wife's acceptance that was the trickiest part. Without the intermediary of the media, their words, on the Chinese equivalent of Twitter, would reach hundreds of millions of people and a single misstep would be magnified, leaving no room for correction.
Here was Ma's post: "It's easy to be in love, but not easy to be in marriage. We must cherish it as we go along (且行且珍惜)."
The last sentence has turned into a meme, popping up on all kinds of occasions and in variations. The Chinese original does not contain any subject or object in grammatical structure. It is quite vague as in classical Chinese poetry. Word by word, it means "walking, cherishing".
Who is doing the walking and cherishing? Is it "I" or "we"? It seems "we" makes more sense in this context as it contains an undertone of mild chiding and forgiving.
The Chinese word "xing" (行) means "to walk" and is often used figuratively to mean "to carry on, to move on" etc. "Cherish" (珍惜) should logically be followed by an object. I added "it", but what does "it" refer to? Does it encompass both "love" and "marriage" in the previous sentence? Or, should I borrow a similarly vague English expression and translate it into "cherish what we have"?
The terseness and ambiguity was quite calculated and, to borrow Shakespeare's aphorism, reflected the writer's "soul of wit". Wen's apology was accused of being too wordy, but Ma showed grace and elegance by using as few words as possible. The poetic convention of the sentence left ample space for imagination, and many members of the public extrapolated an image of a suffering but strong woman who displays an admiringly calibrated sense of clemency.