I am muslim, I don't want to touch any man before marriage, but instantly a fall in love with someone, he is in love with another woman too, he is very good guy and he have Iman. What do you advice me to do? Is it haram to fall in love? Is it haram to make supplication to allah in this setuation? I can't forget him, it's been years since I start loving him, what do you advice me?

We are all human, with feelings, strong ones sometimes, and it's hard to know what to do about them. We cannot always control having those feelings, but we can control what we do about them. Stay within the boundaries of good behavior, and spread that love for one who you cannot attain, or EXPRESS, with others who can receive, and appreciate it in a healthy way, like family and friend.

Always a good idea to seek the counsel of those wiser, that you have trust in, and even ask God for wisdom and strength, and clarity, to deal with your own confusion in your private prayers. The biggest question for you is has this love for this fellow hindered your life in any other way? If it has, if only to distract you from seeing the blessings around you, then the wise counsel of an older, trusted female can also be of help, and support to you.

It's all about finding peace within yourself to continue the journey of life, so peace be with you through this confusing time.

May you find acceptance of this situation and grow beyond it.

There is nothing wrong to fall in love with someone in your case as you stated
I am muslim, I don't want to touch any man before marriage, but instantly I fall in love with someone, he is in love with another woman too
What happens if he will find someone else beside you and his old lover he is cheating on her and will cheat on you too, my suggestion is to follow Talaniman advises, good luck.