I assume this thread is allowing speculative responses, because love is an abstract concept.
In addition to the mating motivation theories, there is a speculative divine possibility.
I have suggested that God is the sum of all matter, which works within my universal theory. God didn't create itself, it never existed at the origin in the sense of the perceived world, because matter (note I didn't write 'mass') does not exist in space-time until it is observed. We create God every day in the perceived world. One plausible explanation of why we are created out of matter, because it is the only way God (sum of all matter) can be perceived (loved?).
My research has added support to the theory that the fundamental matter of the universe is infinite disorder, meaning infinite possibilities[1]. There is nothing outside, because there is no outside. Infinite possibilities includes everything, and explains how the universe wraps onto itself topologically via possibilities, such that the perceived possibilities are always trending to maximum (Second Law of Thermodynamics stated in 1856). Do not think of boundaries in terms of space-time, as space and time are subsets of the realm of infinite possibilities. Review my explanation of the singularity, i.e. black hole, to grasp the how disorder maps space-time back onto itself recursively.
Thus, if my universal theory is true, then it logically follows that the definition of God that I have provided is true, i.e. no assumptions exist since my definition of God is simply a statement of my universal theory.
As to how the matter got there, no human can know, because it is logically impossible for any one to present any theory for the universe, which also explains what it outside the universe. Any theory of the universe will by definition explain only what it explains, i.e. it will only explain what is inclusive of what it explains. The fact that no human can ever know what put the matter there, is for me the proof of a God. How can something be, that was not made. What besides a God could make infinite disorder.
Science is headed for major humbling as the Quantum Information theory is generalized with my Theory of the Universe[1], and scientists are one day forced to accept that they can never know the source of the fundamental matter. Those who ridicule my concept of God or otherwise turn off to my following rational thought, do not understand that the scientific method is a faith that long or fat-tail and Planck's-tail don't exist. At least my universal theory has no such holes and explains the entire extent of the universe. I can find no other theory that does. Even Planck, Einstein, Schrödinger, and Popper understood that assertion of lack of falsifiability is an ephemeral condition, which is not to discourage theoretical investigations:
http://en.wikipedia....#Religious_view
http://en.wikipedia....r.27s_objection