We may have to agree to disagree here, or better, find some common ground of understanding. As you say, love and justice as well as god are most likely the product of social interactions. They are born of the common experience of humans who have an intuition of something which they can not fully express. Matter is also such a thing. Never the less, a materialist conception of the universe might require us to admit that the lepton is something which exists prior to human conciousness and the conceptual discription of this particle, whereas love, for example is anterior to the human conciousness which considers or manufactures it.
Lets say so.
In the case of love for example, such a view might want to speak of the release of hormones such as oxitossin or vasopressin, while the existence of justice, or god, for that matter, would most likely be linked to the need for survival which in the case of humans is strongly linked to group cohesion, shared values and so on. Both love and the lepton exist prior to our conceptualization of them and require this conceptualization in order to be dealt with in a reflective manner by human beings. An analogy is possible here with a certain conceptual compromise made in physics. The phenomena of a baseball interacting with a bat could be fully discribed in terms of quantum physics, however most physicists would probably agree that to do so would involve such enormous levels of calculation as to be overly cumbersome for the purposes of scientific understanding and that conventional Newtonian physics serves this end quite adaquitely even though such physics are not a full discription of what actually happens on the level of physical reality. I can not offer an adaquite argument against this point at the level of purely scientific discourse.