Think about what this text is saying. “For God so loved the world that He gave His only begotten Son.” Does one give good things to those one hates? The answer is no! And one would certainly not give ones best, but that is exactly what God did, he gave is only begotten Son.
Valentines Day is a day in which people think of romantic love but this is not the love that God demonstrated to the world. Romantic love can be a selfish love because romance makes one feel good. The love of God is not a romantic love but a love that is compassionate and gracious. The sinner is the enemy of God, yet God gave his only begotten Son for sinners.
The second part of this text says, “That whoever believes in Him should not perish, but have everlasting life.” Some have made things out of this text that they ought not, considering that the entire context from which this passage comes is a rebirth that comes by the Holy Spirit. It is not a person choosing God, but God choosing the person. One believes in the Son of God because it was granted to that particular person by God. (cf. John 6:37, 44, 65)
Nonetheless, the assurance is without a doubt; whoever believes in the Son of God “should not perish, but have everlasting life.” What is the assurance? The assurance is that the one who made the promise rose bodily from the dead. (John 20:19-20)
His name is Jesus, He is the Christ, the only begotten Son of God. Repent (change your mind) and believe the gospel (good news).