Let us first address a couple of issues before we pray for you. First, it is stated that "We even got into a huge fight last night and I feel terrible about the way I acted." Bickering, arguing, and fighting are not the qualities of a godly marriage or courtship. To the contrary, we are instructed to be kind one to another, tenderhearted, forgiving one another, as God in Christ forgave you. We read in Ephesians 4:31, Let all bitterness, wrath, anger, outcry, and slander, be put away from you, with all malice. In Colossians 3:12-15 WEB, we read, Put on therefore, as God's chosen ones, holy and beloved, a heart of compassion, kindness, lowliness, humility, and perseverance; bearing with one another, and forgiving each other, if any man has a complaint against any; even as Christ forgave you, so you also do. Above all these things, walk in love, which is the bond of perfection. And let the peace of God rule in your hearts, to which also you were called in one body; and be thankful. Let the word of Christ dwell in you richly; in all wisdom teaching and admonishing one another with psalms, hymns, and spiritual songs, singing with grace in your heart to the Lord.
Secondly, there is much discussion on the bed and the size of the bed. This seems to be a complaint more focused on worldly possessions rather than a godly marriage. We are reminded in 1 Timothy 6:6-8 WEB, But godliness with contentment is great gain. For we brought nothing into the world, and we certainly can't carry anything out. But having food and clothing, we will be content with that. Also, in Hebrews 13:5 WEB, Be free from the love of money, content with such things as you have, for he has said, "I will in no way leave you, neither will I in any way forsake you." This is very applicable to your situation.
Thirdly, while you mentioned Jesus at the end of your request, you did not acknowledge Jesus Christ, Jesus, or Christ or an abbreviation such as IJN (In Jesus Name) it is only by the name of Jesus that we have access to God. Also, there is no other name by which we can be saved. We are told in John 14:6 WEB Jesus said to him, "I am the way, the truth, and the life. No one comes to the Father, except through me". The basic salvation message of believing in Jesus Christ is told in Romans 3:23 WEB, for all have sinned, and fall short of the glory of God; Being justified freely by his grace through the redemption that is in Christ Jesus; whom God sent forth to be an atonement, through faith in his blood, to show his righteousness because of the passing over of prior sins, in God's forbearance; to show, I say, his righteousness at this present time; that he might himself be just, and the justifier of him who has faith in Jesus. Also in Romans 10:9-11 WEB, because, if you will confess with your mouth that Jesus is Lord, and believe in your heart that God raised him from the dead, you will be saved. For with the heart, one believes unto righteousness; and with the mouth confession is made unto salvation. For the Scripture says, "Whoever believes in him will not be disappointed."
Now that we have addressed some issues, we can pray for your relationship.
Father God, in the name of Jesus we come to you as the Restorer of all things, and the Healer of broken relationships. We pray for this couple, that you would help them to put away all bitterness, wrath, anger, and malice, and to be kind, tenderhearted, and forgiving to one another. Help them to be content with what they have, and to focus on your kingdom and your righteousness, rather than on worldly possessions. Lord you know this couple wants happiness and peace in their relationship. We pray you intervene and remove the negativity from your fiancé and bring him to a place of thankfulness for his blessings. We pray that he will embrace your will for the relationship and that they will live in harmony and forsake quarreling, being thankful and content with what they have. Help them find the marriage bed undefiled and holy. We pray that they will seek you first, and that they will be transformed by the renewing of their minds, so that they may prove what is that good, well-pleasing, and perfect will of God. We ask all these things in Jesus name. Amen.
We encourage you both to study the word of God, and to seek out a Bible-believing church where you can fellowship with other believers and grow in your faith. May the Lord bless you and guide you in his will for your relationship and for your lives.