It's been 12 years since we have had sex.
The Apostle Paul himself abstained from marriage and gave himself wholly to preaching the Gospel, but he gives the following instruction to baptised believers:
1 Corinthians 7:1-9 Now concerning the things of which you wrote to me: It is good for a man not to touch a woman. 2 Nevertheless, because of sexual immorality, let each man have his own wife, and let each woman have her own husband. 3 Let the husband render to his wife the affection due her, and likewise also the wife to her husband. 4 The wife does not have authority over her own body, but the husband does. And likewise the husband does not have authority over his own body, but the wife does. 5 Do not deprive one another except with consent for a time, that you may give yourselves to fasting and prayer; and come together again so that Satan does not tempt you because of your lack of self-control. 6 But I say this as a concession, not as a commandment. 7 For I wish that all men were even as I myself. But each one has his own gift from God, one in this manner and another in that. 8 But I say to the unmarried and to the widows: It is good for them if they remain even as I am; 9 but if they cannot exercise self-control, let them marry. For it is better to marry than to burn with passion.
If your wife is a Christian, she has a responsibility of compassion towards you as her husband. But out of love, as a Christian, you cannot insist upon it. For you it is an affliction to be borne in this life to be set against the promised glory of the life to come.
Romans 8:18 For I consider that the sufferings of this present time are not worthy to be compared with the glory which shall be revealed in us.
Jesus Christ led a celibate life and then voluntarily endured crucifixion in order to provide us with a way of salvation. We are encouraged in affliction to consider him and the faithful of old who also suffered in this life.
Hebrews 11:35-40 …And others were tortured, not accepting deliverance, that they might obtain a better resurrection. 36 Still others had trial of mockings and scourgings, yes, and of chains and imprisonment. 37 They were stoned, they were sawn in two, were tempted, were slain with the sword. They wandered about in sheepskins and goatskins, being destitute, afflicted, tormented 38 of whom the world was not worthy. They wandered in deserts and mountains, in dens and caves of the earth. 39 And all these, having obtained a good testimony through faith, did not receive the promise, 40 God having provided something better for us, that they should not be made perfect apart from us.
Hebrews 11:1-13 Therefore we also, since we are surrounded by so great a cloud of witnesses, let us lay aside every weight, and the sin which so easily ensnares us, and let us run with endurance the race that is set before us,2 looking unto Jesus, the author and finisher of our faith, who for the joy that was set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God. 3 For consider Him who endured such hostility from sinners against Himself, lest you become weary and discouraged in your souls. 4 You have not yet resisted to bloodshed, striving against sin. 5 And you have forgotten the exhortation which speaks to you as to sons: "My son, do not despise the chastening of the LORD, Nor be discouraged when you are rebuked by Him. 6 For whom the LORD loves He chastens, And scourges every son whom He receives. 7 If you endure chastening, God deals with you as with sons; for what son is there whom a father does not chasten? 8 But if you are without chastening, of which all have become partakers, then you are illegitimate and not sons. 9 Furthermore, we have had human fathers who corrected us, and we paid them respect. Shall we not much more readily be in subjection to the Father of spirits and live? 10 For they indeed for a few days chastened us as seemed best to them, but He for our profit, that we may be partakers of His holiness. 11 Now no chastening seems to be joyful for the present, but painful; nevertheless, afterward it yields the peaceable fruit of righteousness to those who have been trained by it. 12 Therefore strengthen the hands which hang down, and the feeble knees, 13 and make straight paths for your feet, so that what is lame may not be dislocated, but rather be healed.
If the problem is still more that you can cope with, marriage guidance counselling might be an avenue to explore, if your wife agrees.
I hope you find this helpful.