I think there is a perception that the middle way is very narrow. You discover the Dhamma, place your faith in it, and aim for the cessation of suffering - ignoring everything else. In my opinion, this is only one side of the road - a necessary one, because without right effort progress along the path is not possible.
Theravada Buddhism aims to attain this state of Arahantship. Mahayana Buddhism aims for the Bodhisattva ideal however, where the individual practices the path for the well being of all life on earth. This is no different from the Arahant ideal, but the framing can be seen as different. Like two sides of the road - one side concentrating on the internal, the other concentrating on the external.. it would also make sense that the Noble Eightfold Path is not some 'extreme middle ground', as the Buddha asked his followers to cast off all extremes. And either utterly detaching yourself from the world for your own aim (at the expense of the world), or utterly attaching yourself to the world for its benefit (at the expense of your own progress) are both extremes!
As for craving, there is no need for it within normal relationships. A Buddhist practitioner of any denomination would strive to practice the four immeasurables: loving kindness, boundless compassion, altruistic joy and equanimity (found within the Metta Sutta). A lasting bond does not require the craving for that bond to continue for ever (evidently impossible anyways!), the above four virtues are enough. It is also hard to argue how any individual who practices the above could be seen as 'detached' in any way that would be perceived as negative.
Equanimity, Upekkha, is not indifference incidentally.. best to quote Bhikkhu Bodhi:
“The real meaning of upekkha is equanimity, not indifference in the
sense of unconcern for others. As a spiritual virtue, upekkha means
stability in the face of the fluctuations of worldly fortune. It is
evenness of mind, unshakeable freedom of mind, a state of inner
equipoise that cannot be upset by gain and loss, honor and dishonor,
praise and blame, pleasure and pain. Upekkha is freedom from all
points of self-reference; it is indifference only to the demands of
the ego-self with its craving for pleasure and position, not to the
well-being of one's fellow human beings. True equanimity is the
pinnacle of the four social attitudes that the Buddhist texts call the
'divine abodes': boundless loving-kindness, compassion, altruistic
joy, and equanimity. The last does not override and negate the
preceding three, but perfects and consummates them.”
For the bully example, the Dhammapada starts off with:
“He was angry with me, he attacked me, he defeated me, he robbed me” -
those who dwell on such thoughts will never be free from hatred.
“He was angry with me, he attacked me, he defeated me, he robbed me” -
those who do not dwell on such
thoughts will surely become free from hatred.
To the bullied child, this is the simplest advice (as well as the advice to practice the four virtues towards the bully).
As for the bully, the Buddha gave a discourse to his son, Rahula, in Majjhima Nikaya 61 http://www.accesstoinsight.org/tipitaka/mn/mn.061.than.html
"Whenever you want to do a bodily action, you should reflect on it:
'This bodily action I want to do — would it lead to self-affliction,
to the affliction of others, or to both? Would it be an unskillful
bodily action, with painful consequences, painful results?' If, on
reflection, you know that it would lead to self-affliction, to the
affliction of others, or to both; it would be an unskillful bodily
action with painful consequences, painful results, then any bodily
action of that sort is absolutely unfit for you to do. But if on
reflection you know that it would not cause affliction... it would be
a skillful bodily action with pleasant consequences, pleasant results,
then any bodily action of that sort is fit for you to do.
"While you are doing a bodily action, you should reflect on it: 'This
bodily action I am doing — is it leading to self-affliction, to the
affliction of others, or to both? Is it an unskillful bodily action,
with painful consequences, painful results?' If, on reflection, you
know that it is leading to self-affliction, to the affliction of
others, or to both... you should give it up. But if on reflection you
know that it is not... you may continue with it.
"Having done a bodily action, you should reflect on it: 'This bodily
action I have done — did it lead to self-affliction, to the affliction
of others, or to both? Was it an unskillful bodily action, with
painful consequences, painful results?' If, on reflection, you know
that it led to self-affliction, to the affliction of others, or to
both; it was an unskillful bodily action with painful consequences,
painful results, then you should confess it, reveal it, lay it open to
the Teacher or to a knowledgeable companion in the holy life. Having
confessed it... you should exercise restraint in the future. But if on
reflection you know that it did not lead to affliction... it was a
skillful bodily action with pleasant consequences, pleasant results,
then you should stay mentally refreshed & joyful, training day & night
in skillful mental qualities.
The bully's actions will end up having negative consequences (karma) for himself through his own wrong actions. Having compassion for him, the parent of the bullied kid should try and explain this to him and his parents, but if they do not listen then it is for them to learn for themselves. Buddhism denies the ideology of violence, whether physical or mental, therefore no method beyond 'think, speak and act by example' is embraced.
It is interesting to point out that the Buddha as depicted within the Tripitaka was not detached in the way you perceive of Buddhist monks. He formed a life long relationship to those within his Sangha, even if not defined within the framework of having any desire for such a relationship. In fact, because he lead a homeless life dependent on the food of householders, he was engaged with the world as a whole. I have yet to read of him rejecting an offer to teach the Dhamma to anyone within the Sutta Pitaka, including those that threatened his life. In my opinion, he tread the whole middle way, engendering both the detached Arahant ideal, as well as the Bodhisattva ideal of being (not wishing, since he was the Buddha after all!) for the benefit of all beings. The two ideals don't exclude but rather reinforce each other - it is much easier to be filled with loving kindness for all when there is no desire for one's own self to interfere in the equation!