Are we, indeed, allowed to love anyone whom we care for (like Rahel and Estha)?

This is a fairly sensitive issue and will not have a
reductive and easy answer.  There are some fundamental issues that need to be addressed
here.  Some of them are in the context of Roy's novel and some are outside of it.  The
basic answer is that that are social, cultural, and/ or legal barriers that prevent
anyone from loving anyone for whom they care.  That being said, Roy is making the
argument that there are some types of passions that lie outside the domain of social,
cultural, and even legal mores and practices.  These fundamentally powerful expressions
of love and desire are kept in check to a great extent by these forces.  Yet, there are
some points, as with Rahel and Estha, where this has to be expressed.  Roy's argument is
that in these cases, the barriers that seek to divide and separate do not fully
understand the intensity and purity of such a love.  Upon reading the novel, one can
determine for themselves if Roy is accurate in her claim.  I would say that while Roy
presents a compelling case, I think that there has to be some level of adherence to
these barriers in order to prevent this desire from entering realms where there is a
greater chance of hurt and emotional damage than anything else.  The discussion of
incest or hopeless love might fall into this category.  I would say that there is little
progressive or redemptive opportunity for an incestuous or hopeless love to prosper, if
acted upon.  In these situations, it might be best to heed the social, cultural, and/ or
legal positions that forbid.  This might appear rather prudish, but I think that it is
conceived out of a position to minimize pain.  Along these lines, if such behavior was
sanctioned, then I think that it can lay the groundwork for actions that can be
manipulated into being "profound" expressions of love, but actually be self- serving and
ones that seek to take advantage of another.  A good example of this would be
the Orangdrink Lemondrink Man at the Abhilash Talkies theater who sexually abuses Estha.
 This is a situation that could very well be justified as "passionate," but is really
conceived out of a self serving desire to control one person for the selfish benefit of
another.  While there is a risk of forbidding passionate love, I think that the
adherence to some examples of cultural and social mores and all legal ones helps to
protect individuals from situations upon which they can be prey or from which they can
prey on others.  I think that in this light, I would say that we are not allowed to love
anyone for whom we care in a light that would be deemed as
unacceptable.