A practitioner should stay detached when circumstances so require, and remain attached if attachment is called for. When cultivating bodhicitta, attachment is essential. Sakyamuni Buddha said that at that point our self-attachment should be bigger than Mount Meru — I want to attain Buddhahood, I want to free all sentient beings from suffering, I want to undertake actions that are beneficial to others, etc. This kind of self-attachment is indispensable at the beginning; with practice, one gradually dispels the wrong kind of self- attachment, creates the conditions for realizing emptiness and compassion, and ultimately eradicates all forms of attachment. Thus, the delineation between attachment and non-attachment must be very clear.
~Depicted from THE FOUR SEALS OF DHARMA - The Practice of No-Self