The calculated wisdom of the 'first wife'
The public attitude toward the first wife is one of ambivalence. She has always taken the moral high ground as she is the legally wedded spouse, but culturally she is often portrayed as old-fashioned, temperamental and, in the old days, even illiterate. In the early 20th century, many men, especially writers and artists, would "adopt" younger wives - not trophy wives, mind you, but kindred spirits - but they would financially support their first wives, who would otherwise be mired in poverty. There was hardly a love story told from the perspective of the first wife.
In this day and age, the first wife cannot be stashed away. She may be older in age (in Ma's case, six years older than the girlfriend and eight years her husband's senior) and she often exhibits more maturity. Flying into a fit of rage or revenge might be melodramatic, but those who are cool as a cucumber and get their straying husbands back without making a scene are highly regarded.
In Feng Xiaogang's acclaimed film A Sigh, the first wife runs into the girlfriend and invites her into her home. Instead of threatening the younger woman or prying her about details of the infidelity, she calmly recounts the early years her husband and her met and dated. By the end of her narration, the girlfriend leaves - in despair. It has dawned on her that the man she is in love with has loved another one just as ardently and may well repeat this cycle. She is by no means his one and only, not now and possibly not in the future.
Similar scenes are more and more accepted in Chinese family drama. Ma Yili, playing a real-life first wife, is exemplary in this new tradition.
She did not use the word "forgive", nor did she come across as moping and pathetic. She held her head high.
Maybe by "cherish", she also meant that her husband should hold dear what she's doing now. Maybe next time she would not be so forgiving.