A lot of people simply don't understand what the Church means when she says something is a "mystery". Too often we focus on the negative aspect, that this is something which will never be fully understood (by any human) either in this life or the next. Seldom is it mentioned that while not capable of being fully understood, we may still come to a much better understanding than the one we presently hold. Reason and reflection can take us far deeper than we presently are, and since God is our Divine Beloved we ought to want to know as much about Him as possible. Would you settle on merely knowing your spouse's name? Of course not! You want to know everything about them, and you can sometimes glimpse that even after a lifetime together your spouse will still find ways to surprise you. That's how it is with God -- and that's why He gave us spouses, so that we can glimpse the truths about Him. (For more info on this last point, see the lectures in the Theology of the Body section of my blog.)
With this in mind, I invite you to grow deeper in your understanding of the Most Holy Trinity. Come, know the God who is Love.