Synchronicity may be explained by angels.
Synchronicity usually refers to happy and extraordinary occurrences in life, when it feels that things have been arranged for one's personal benefit.
I have found that it occurs in a particular mood or emotional state, when I just know that things are building-up towards a synchronous event.
Reflecting on the meaning of synchronicity was a factor in my becoming a Christian - as it implies that the universe is, to a significant extent, interested in me as an individual, which implies a 'personal God'.
But I hadn't thought much about the mechanisms of synchronicity - how such events might be effected in practice.
Then reading (again) about angels (and demons) in Peter Kreeft's book on the subject, I realized that the properties of Guardian Angels, as he describes them, drawn from the writings of Aquinas and others, would be a plausible explanation of to effect synchronicity.
Angels have greater knowledge than humans, greater intelligence, can move very fast, can effect change in the world, and communicate with humans (especially by emotions and general ideas) - and using these abilities to generate synchronicitous events would be a good method of helping specific humans (that being the role of guardian angels).
Of course, human will necessarily remains free - and a synchronicity leads to a choice which could go either way; and humans are free to interpret anything as a meaningless coincidence if they choose; but presumably angels do what they can, within such necessary constraints.