Well, this is one of those questions/threads where people will inevitably have many different views and experiences given the highly subjective nature of what everyone feels/defines as love. I personally don't have only one definition and much prefer to see love as a sort of umbrella term... not only that, but also something that can be very dynamic and change throughout a person's life. So I won't get into defining what love means for me, because it does not mean just one thing. I also don't tend to jump to the perception of its being romantic/sexual as my first thought - I actually think that immediate perception is a bit immature or perhaps sometimes carries some wishful thinking.
I definitely think love is possible between therapist and client, and in many different ways. I can't say I experienced anything that I would describe as love in my therapy (what I had was more the occasional liking, appreciation, respect, gratefulness), I think mostly because I did not engage in therapy too long and in a very relational way and so did not care about the Ts in a very deep, personal sense, the way I do in other relationships. But I get it and see it reported here on PC all the time, I don't doubt it at all. I do also think that a lot of therapy and the therapist's persona is a fantasy or illusion, but people can perfectly love illusions and fantasies - I will even risk that perhaps we more often do that than loving hardcore reality. I also do not believe that it is necessary to know someone in great detail to develop loving feelings (or intimacy). The one thing, for me, that seems to be a condition for feeling love for someone beyond just enthusiasm or infatuation in the moment is mutuality. I know this is not the case for everyone but it's been the pattern throughout my life, my personal experience. It does not mean that both people are flooded by an acute feeling of love at the same time but, for me, there has to be a background sense that it is present and mutual in an overall way in a relationship. I also share views with those who feel that it does not really need to be put in words - for me it is usually very obvious and better not to break with demands for reassurance and too much analysis. If the above condition is not met, I can still experience very positive feelings and attachment, but it is more in the range of what I said above: liking, appreciation, respect, gratefulness etc.
DP, I really like how you use this forum to express something important to you and do not get the occasional negativity to silence you or to engage in resentful petty arguments. That is a quality that I often associate with maturity
BTW, and this may sound a bit too clinical, I personally do not believe that any earthly love is truly unconditional, including the parents' love for their children or what we experience with animals. I am saying it is clinical because, when I think/talk about this, I approach it from the point of view of a biologist/neuro/behavior scientist that I am... but that would be too much off topic for this thread and would not add to the discussion.