Love is a feeling that goes much deeper than our physical actions.  I can conceive of a person who acts as though they love somebody when they actually do not.  I can conceive of a person being in denial of their own love for somebody else.

So love is a very tricky concept, and I think it's unfair to claim that we have a concise definition for what it is and a complete understanding of how it works on a subjective level.  Likewise, I think it's premature to say that particles cannot love until we fully understand how it is that we can love, be conscious, have psychedelic experiences, etc.

What I'm trying to say is that love is a completely subjective phenomenon, and thus it is not for me to decide whether or not other people or particles love.  Only from a particle's subjective viewpoint can it's ability to love be evident.  I am the only being that bears witness to my consciousness, and the same is true of particles with respect to their consciousness, whatever that may consist of.