There is any reason whatsoever that the Dad can’t still love his son. He doesn’t have to condone the relationship at all either.
If the son were in involved in any other sinful situation, the Dad would still love his son, hug his son, be supportive, but would not condone the sin.
For example, if he had a married son who confessed to adultery, the father would love his son, comfort his son, but also insist that he stop seeing the other woman, and return to his wife to work out issues in his marriage.
Name any other sin, and I think we all know that the dad would encourage his son to stop the sinful behavior.