It is not degenerate to find sexual gratification in images you and your spiritually committed life partner make for each other, or to have a shared sexual experience with your life partner together over the phone or video. As long as it's just you two, it's the same as sex. The marriage bed is NOT defiled, ever. It is redeemed, no matter what happens there. Just keep it between you and your life partner, and your union will be blessed by God.
"Let marriage be held in honor among all, and let the marriage bed be undefiled, for God will judge the sexually immoral and adulterous." - Hebrews 13:4
Let your fountain be blessed, and rejoice in the wife of your youth, a lovely deer, a graceful doe. Let her breasts fill you at all times with delight; be intoxicated always in her love. - Proverbs 5:18-19
To the rest I say (I, not the Lord) that if any brother has a wife who is an unbeliever, and she consents to live with him, he should not divorce her. If any woman has a husband who is an unbeliever, and he consents to live with her, she should not divorce him. For the unbelieving husband is made holy because of his wife, and the unbelieving wife is made holy because of her husband. Otherwise your children would be unclean, but as it is, they are holy. But if the unbelieving partner separates, let it be so. In such cases the brother or sister is not enslaved. God has called you to peace. For how do you know, wife, whether you will save your husband? Or how do you know, husband, whether you will save your wife? - 1 Corinthians 7:12-16
What makes the marriage bed Holy is single-minded, unviolated sexual committment to ONE person before God and men. Loyalty.
What defiles the marriage bed is not whether or not your partner is saved, and not the acts you perform together, what defiles the marriage bed before God is allowing others into your sexual and spiritual union.