"I will love you forever" is a romantic exaggeration. Romance and sexual attraction are a biological process, which is linked to a man and wife becoming one. Love in Christ transcends this relationship, and intimacy is about trust, openness and sharing, which is the communion of the saints. You just have to look at what happens when unsaved people get close to each other, often fireworks and hurt arises, followed by revenge and brokenness, followed by real loneliness.
Because communion and being in the Lord transcends sexuality these things will fall away in the Kingdom.
I am shocked by the lack of understanding of what being an individual is, and what sharing one with another is all about. "Who knows and loves the real me" is often the hearts cry. "I am all alone".
But Jesus says no, I am with you, and your brothers and sisters in Christ. Feelings are like the weather, storm clouds, lashing rain, and then bright sunshine and clear wonderful days. We want attention, recognition, contribution and our own space. Once you stop defending hurt, and let the pain flow and be healed, you begin to see the problem of a sinful world always trying to keep that which is not theirs. I know too many people who under their defences have never let themselves feel and express one authentic feeling. If I share with them joy or sadness, it must be destroyed because it must be a joke because everyone is like them.
I went on a marriage introduction course before we were married and the couple kept on bickering over who was more important in their previous jobs, from which both of them had retired, lol. Break this down a little they wanted the other to feel "they" were better ..... But maybe, maybe not. How was this relevant? They were in this emotional merry go round of put downs and proving ones value. Jesus simply says, "I love you." Each is unique and gifted and learning to see the strengths in each through everything makes the whole the body of Christ.
Being a couple is just part of the worlds situation, which is transcended by the eternal.
God bless you