In reality, friends of the opposite sex always send me I love you to death when chatting on QQ, and then give me an ambiguous expression continuously. How should I reply?

Then you should pay attention, there are three possibilities: first, he may like you. In this case, you must try to verify it. You can tell him for sure that you don't like his indecency, because you might scare him with something serious and see his reaction. Second, he is a playboy in reality and likes to flirt with girls for fun. Such people don't have to be serious or angry with him, so they should be cruel when they speak. Third, I may have a good relationship with you, so I say it in good faith. In fact, many people are used to it now. Why do I love you so much? It's no fun to give a hug and kiss. You won't feel bad after you get used to it. You got it?