even when my affections change, I know he is unchangeable

"He changes not in His attributes. Whatever the attributes of God were of old, they are the same now. And of each of them we may sing, As it was in the beginning, is now and ever shall be, world without end, Amen. Was He powerful? Was He the mighty God when He spoke the world out of the womb of non-existence? Was He the Omnipotent when He piled the mountains and scooped out the hollow places for the rolling deep? Yes, He was powerful then and His arm is unpalsied now. He is the same giant in His might. The sap of His nourishment is still wet and the strength of His soul stands the same forever. Was He wise when He constituted this mighty globe, when He laid the foundations of the universe? Had He wisdom when He planned the way of our salvation and when, from all eternity, He marked out His awful plans? Yes and He is wise now. He is not less skillful, He has not less knowledge. His eyes which see all things are undimmed. His ears which hear all the cries, sighs, sobs and groans of His people, are not rendered heavy by the years which He has heard their prayers. He is unchanged in His wisdom. He knows as much now as ever—neither more nor less. He has the same consummate skill and the same infinite forecasting. He is unchanged, blessed be His name, in His justice. Just and holy was He in the past—just and holy is He now. He is unchanged in His Truth—He has promised and He brings it to pass. He has said it and it shall be done. He varies not in the goodness, generosity and benevolence of His nature. He is not become an Almighty tyrant, whereas He was once an Almighty Father. His strong love stands like a granite rock unmoved by the hurricanes of our iniquity. And blessed be His dear name, He is unchanged in His love. When He first wrote the Covenant, how full His heart was with affection to His people. He knew that His Son must die to ratify the articles of that agreement. He knew right well that He must rend His best Beloved from His heart and send Him down to earth to bleed and die. He did not hesitate to sign that mighty Covenant. Nor did He shun its fulfillment. He loves as much now as He did then. And when suns shall cease to shine and moons to show their feeble light, He still shall love on forever and forever. Take any one attribute of God and I will write semper idem on it (always the same). Take any one thing you can say of God, now, and it may be said not only in the dark past, but in the bright future. It shall always remain the same—“I am Jehovah, I change not”—impressed on His heart it remains."
- Charles Spurgeon