The mindfulness-based injunction to not grieve can be misunderstood. As I am waddling through my own grief, it is becoming more clear that one is not to indulge in the proliferation of grief related thoughts. AND, at the same time, one is not to ignore the waves of grief-related emotions that keep on surging from the heart.
'Do not grieve' is an impossible goal for the ordinary humans that we are. Hindrances in the unenlightened or partially enlightened mind make it such that clinging is present still, which leads us to experience great suffering when our love one leaves us permanently. This non negotiable goodbye brings our grasping tendencies to the forefront of our consciousness, and we get to feel the painful consequence from our binding and impure love.
If we try to hasten the 'not grieving' process, we run the risk of repressing the grief. Not a good thing, as I learned many years ago when I could not face up to the reality of my emotions when my father died. The dis-owned grief came back to crush me a year later, in the form of a disabling breakdown. We are to recognize the emotions that rise up, all of them, without judgment. We feel them, we give them space to be, and we move on with the next moment.
Conversely, we do not want to overindulge grieving thoughts. Such over thinking is only an expression of the mind-created self running wild. It is easy letting the mind create stories about the dead person, and ourselves in relation to the person. Wishful stories, guilt ridden thoughts, embellished tales . . . are all fabrications that keep us stuck in the suffering from unnecessary clinging. To let go of the urge to think such thoughts, I have found it helpful to contemplate Ayya Khema's talk on Metta, especially this:
The near enemy of love is attachment. [...]