What is love
It is hard to ever really find one unified definition of the concept, but I divide the idea into two separate categories: feeling and choice. Love is a feeling that captures you before you can fathom it. It is the experience of bliss towards something or someone. Alternatively, as a choice, love can be described as a decision or a series of choices one makes in order to provide the feeling of love in the manifestation of acts towards anything or anyone. These two perspectives of love aren't insulated from one another, as they can, and often do, overlap.
What is it to invent?
To invent is to create.
Conscious and subconscious processing
One more important distinction is that between conscious and subconscious processing. Our mental capacity is made of both conscious and subconscious processes. The conscious being that which lays apparent in our awareness; the feelings and thoughts we identify with. The subconscious processing is that which occurs in the background, outside the perception of the conscious self (if that does exist (in reference to the self)).
Is love an invention?
Having understood the concepts, we can now delve deeply into the mystery: "Is love an invention?" This question had come to me from a friend who I had recently met; we were discussing the existence of reality. I had prompted the discussion because I had felt in that mood to question all that is true about our fundamental reality (I just wanted a debate). I raised the proposition to my new acquaintance that our values did not exist in the outside world and were a mere reflection of a mind-dependent reality that was insulated from objective reality. Her response was that my idea was stupid; this triggered me and made me go on the defensive. She then proceeded to ask me, since I claim values are nothing but an invention, "If love is a value, then who invented love?" The question got me hung, one because her "stupid" remarks had triggered me, but as well, her question didn't seem to be in line with what I had constructed in my head. In my head, values were merely a construct used to concretely narrow down the abstraction of our perception of reality, but nevertheless, her question made me think and wonder, Who really invented love?
My case
Earlier, "invent" was defined as being the ability to create. My friend's understanding of my claim was that values (love) are something that we create as a result of conscious effort to have the experience, and while this type of creation could be argued for the definition of love that centers around the idea that love is an action or set of actions, it doesn't align with the message I was trying to pass along. Love as an action can be defined, accepted, and acted upon, and this falls under the concept of an invention, but the version of love I was alluding to was focused, which occurred beyond the conscious processes of humans. This type of love doesn't emit from our conscious intentionality to create; rather, we take the passenger seat here. This love is an experience that captures us, and we usually have no choice but to allow it to direct us. It may not have been invented with intention (this is a subjective matter, as one could argue that it could), but part of the long line of evolutionary processing that has led us to where we are. The invention wasn't that of conscious awareness, but an invention nonetheless. Our perspective of reality is not reality. What we witness and experience exists as a distorted version of reality, thanks to our senses. The feeling of love changes the perception and importance of a being, whereas such change doesn't reflect on reality. The loved object still remains what it is; no value is added or subtracted from the being except through the mind of the conscious being. This distortion is not limited to love; it occurs in a whole lot of human affairs. We have perceptions of reality that change what things mean, how they feel, and what value we give to them. One could argue that our subjective interpretation is an objective fact of the universe, but that doesn't refute the fact that the interpretation itself is mind-dependent to the individual or the collective.
Limitation
Because I'm not as familiar with philosophical concepts as I'd like to be, I have missed some important points, but I promise to improve as I go on. For now, this is my opinion on love being an invention.