Ridiculous. If the natural state of the world is "suffering, sex, and death," it's also joy, sex and birth. Sex is at least value neutral -- if you are going to sandwich it between suffering and death I may as well put it between joy and birth -- which are real experiences. Animals seem to experience joy, to play, etc.

Animals also take care of their young, they often mourn those who died.

Plus, your incredulity at the thought of "love" between single-celled organisms is without basis. Love is a subjective state which we can only infer. We (well, some of us, not you I guess) think it's real because we've felt it at a level to which to describe it as not real would do violence to our conception of real/unreal.

And then we infer that it's felt in other organisms around us based on their actions.

Now, a single-celled organism really doesn't have a great range of "actions/behaviors" it can show us. Therefore we don't get to see it. This says nothing about whether it's experienced or not.