He acted on the basis of his feelings alone and it led to adultery, murder, deceit and the disintegration of his family. We have to come back to the Word of God. That was Jesus approach. The problem is that if we fall in love with anyone in these categories, the feeling may be so strong that we are tempted to think we should act on it. If we do we are on the road to disaster.
Mixed marriages are out.
But she was a Jew in the sense of having faith in God. It's not race that's important, or even age. You don't need to be romantically involved with someone to explain the Gospel to them. It causes far more pain for God to see a Christian continuing in a wrong relationship and obstructing the work of the Gospel. He should never have got involved in the first place.