After reading your query, I think that maybe the guy likes you too or maybe it is in his nature to help everyone or maybe you were new to the office so he helped you. There could be innumerable reasons. Don't fall in the vicious circle of those reasons.
It could be possible that he likes you too but he is not able to man up and tell you about his feelings. He may be going through the same confusions you have regarding him.
Right now I personally think you are only attracted to him. Take time and know him. It's a matter of life. It may sound all dreamy and romantic but remember even dreams are difficult to achieve and romance often gets misunderstood.
But since you say you want him in your life, that too for good, then don't hesitate. Summon your courage and ask your colleague for his number. Text him and talk to him. If possible, hang out with him as people often conceal a lot in texts but in person, we get to know a lot about them. Try to be a friend first. I am suggesting you become a friend first because a friend knows all the good and bad things about the person he/she is friends with. Even after knowing everything about him, you still like him and want to be with him then you must confess him. If he likes you, and you guys talk and meet, he too will get to know about you. If he continues to like you even after that, he may confess even before you do.
But if he ignores you, or continues to talk like a colleague, not even a friend, then remember he doesn't feel the same for you. Some people like to help others and we may feel that they have a thing for us but in reality, they only intend to help us.
In such a case, I would suggest you let him remain a crush and move on in life. You may find someone else, someone better than this guy. It may seem way too magical and you may not be able to remove him from his mind now, but trust me it happens with everyone. It is nothing exclusive.
Yet if you think you should try a bit more to be with him, then proceed at your own risk. Because it also happens that when someone realises our love for them, they tend to love us even more than we love them. It may or may not happen in your case. Whatever the consequence is, remember you must never regret. Life is short. You tried to fulfil a dream of yours. Not everyone can man up to do that. You did that.
All the best. May you find the one you want to be with for the rest of your life.
Make love to life before it divorces you.