How do philosophers explain phenomenons like coincidence? ?

Bishop Berkeley, for example, posits a Unity of Spirit which acts on the spirit of a man as ideation.  There are no coincidences in the Reality.

Dr. Marie-Louise von Franz, a colleague of Jung, and who worked with Wolfgang Pauli, furthered Berkeley's ideas via the Archetype model of spirit-of-men as a hidden dimension:  "Archetypal Dimensions of the Human Psyche". 

Leibniz noted the number 1 as representing all power; "...as all numbers are derived from one plus one, so must all multiplicity be derived from unity."  Leibniz' 1 ~ = Bishop Berkeley's Unity ~ = Energy ~ Descartes' One Idea, God, I Am *that* I am ~ = Plotinus' One Mind Soul.

Related:  "Return to the One:  Plotinus's Guide to God-Realization."

With a dictionary.  

They explain coincidences as coincidences.  Two things that appear to be related but are not.