"Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh." Gen 2:24
"Yet an elder needs to be one who is without blame before others. He should be one whose heart is for his wife alone and not another woman. He should be recognized as one who is sensible, and well-behaved, and living a disciplined life. He should be a “spiritual shepherd” who has the gift of teaching, and is known for his hospitality." TPT, I Tim 3:2
"Marriage is honourable in all, and the bed undefiled: but whoremongers and adulterers God will judge." Heb 13:4
"But fornication, and all uncleanness, or covetousness, let it not be once named among you, as becometh saints; Neither filthiness, nor foolish talking, nor jesting, which are not convenient: but rather giving of thanks. 5 For this ye know, that no whoremonger, nor unclean person, nor covetous man, who is an idolater, hath any inheritance in the kingdom of Christ and of God." Eph 5:3-5
"But whoso committeth adultery with a woman lacketh understanding: he that doeth it destroyeth his own soul." Pro 6:32
'Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband." I Cor 7:2
"Mortify therefore your members which are upon the earth; fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry:" Col 3:5
"Thou shalt not commit adultery." Exo 20:14 "Ye have heard that it was said by them of old time, Thou shalt not commit adultery: 28 But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart. And if thy right eye offend thee, pluck it out, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into hell. 30 And if thy right hand offend thee, cut it off, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into hell." Matt 5:27-30
There are more Scriptures on this topic. But these are some of God's thoughts about how He expects us to behave before Him.