If the modern translations give you the impression that fornication is ok then there is a problem with those translations, the Bible does not change so if the modern translations do not convey the true meaning as Christians have held it since the time of Christ then those Bibles are no good.
In the Bible I use God is quite clear in this matter.
adtende tibi fili mi ab omni fornicatione et praeter uxorem tuam numquam patiaris crimen scire [FONT=Times New Roman, Times, serif]Tobias 4:13[/FONT]
Take heed to keep thyself, my son, from all fornication, and beside thy wife never endure to know a crime. [FONT=Times New Roman, Times, serif]Tobias 4:13
[/FONT]non erit meretrix de filiabus Israhel neque scortator de filiis Israhel [FONT=Times New Roman, Times, serif]Deut. 23:17[/FONT]
There shall be no whore among the daughters of Israel, nor whoremonger among the sons of Israel. [FONT=Times New Roman, Times, serif]Deut. 23:17
[/FONT]ut abstineatis vos ab immolatis simulacrorum et sanguine suffocato et fornicatione a quibus custodientes vos bene agetis valete [FONT=Times New Roman, Times, serif]Act. 15:29[/FONT]
That you abstain from things sacrificed to idols, and from blood, and from things strangled, and from fornication; from which things keeping yourselves, you shall do well. Fare ye well. [FONT=Times New Roman, Times, serif]Act. 15:29[/FONT]