There is an opinion that there can be no friendship between a man and a woman, because over time, passion will certainly flare up. And if it happens that your friendship has developed into love, you can try to take the relationship to a new level by achieving reciprocity.
Think about whether you really fell in love. The fact is that your feelings may turn out to be nothing more than a hobby, and if you try to conquer your friend or girlfriend, and then grow cold, then it will be too difficult to return the old trusting relationship.
Control yourself and take your time. You might want to do things that friends don't do: get a kiss, have a romantic evening, etc. Do not allow yourself too much, because otherwise you can unpleasantly surprise and even alienate your loved one, turn him against yourself.
Remember everything you know about your loved one, and especially about his relationship with the opposite sex. Friends often talk about even the most personal, so you can probably easily understand what the ideal partner is for your friend, what a love relationship should be from his point of view, etc. Strive for excellence and don't give up trying to get your loved one's attention.
Do what pleases your friend. You probably know that he loves more than anything, what he enjoys, what he dreams of. Show courtesies, and start with small but nice gifts. You can present them with or without reason.
Try to spend more time together. Go to the cinema, cafe, theater, etc., walk, attend concerts, do your common hobby. Try to ensure that your friend is used to you and needs your company.
Don't be afraid to touch your loved one. As a friend, you can afford to hug, take a hand, pat on the shoulder. Add more intimate gestures: for example, you can pretend to remove an eyelash from your face, and under this pretext, run your hand over the cheek of a loved one. Watch his reaction.
Go on a short trip together. It can be either a hike or a visit to a recreation center, a hitchhiking trip, etc. The main thing is that you are alone. Try to add some romance. And finally, if you feel that your loved one is good with you, confess your love to him or at least hint about your feelings.