Thank you for sharing this burden and allowing me to pray with you. I hear your concern for your boyfriend as he faces this procedure and the possibility of discomfort leading to a flare up, and I want to bring that concern to the Lord with you.
Scripture shows us that Jesus bore our infirmities and sicknesses, as Isaiah foretold and Matthew confirms when he writes that Jesus fulfilled what was spoken, surely he has borne our griefs and carried our sicknesses. Throughout the Gospels we see His power over sickness in many different ways. Sometimes He healed instantly with a word, sometimes with a touch, sometimes He healed gradually, and sometimes He healed from a distance without even being present. He was not confined to one pattern, and that reminds us that God is free to work as He wills.
I believe very strongly that God still heals today. All true healing is from Him. He has built healing processes into our bodies, and those natural processes are themselves divine because He created them. At times He heals in a moment in a way we can feel, at other times He heals gradually through the body's recovery, through the wisdom He gives to doctors and medical care, and at other times He brings healing to the mind and heart, calming fear and bringing peace even while the body is still struggling.
At the same time there is much about healing we do not understand. We do not know why some are healed quickly and others are not, and we should never assume that sickness or ongoing symptoms mean a person has sin in their life or lacks faith. Even the apostle Paul prayed three times about his own thorn in the flesh and was told that God's grace was sufficient, and he left a fellow worker behind because he was sick, and spoke of his own infirmities. Sickness is not a simple measure of spiritual strength, and healing evangelists who whip people into frenzies or promise healing for everyone or blame the sick do great harm. We can trust God's goodness and power without making false claims about His will in every case.
So I will pray for your boyfriend, asking the Lord in the name of Jesus Christ, through whom alone we have salvation and access to the Father, to have mercy on him during this procedure. I will ask that the Lord would guide the hands and minds of those caring for him, that discomfort would be limited, that a flare up would be prevented if it be the Lord's will, and that God would grant him peace and strength. I will also pray for you, that God would give you peace as you care for him and that both of you would grow in trusting Jesus and walking in His ways. God designed our lives and our relationships for our good, and His best for intimacy and commitment is found within the lifelong covenant of marriage between one man and one woman, so I encourage you both to seek Him for wisdom and purity in your relationship as you seek Him for health.
May the Lord be near to you both, give you calm hearts, and help you to rest in His love and sovereign care whatever the outcome, knowing that He hears the prayers offered in Jesus name.