Is a husband entitled to spend the night outside the marital home with his friends at a chalet, even though his wife disapproves and is harmed by it, especially given that she asked him to return before bedtime so she could sleep in her home, and he justifies his actions by saying that his married friends do the same?

The correct view is that the husband should spend the night in his home for as long as it takes for the feeling of loneliness to dissipate from his wife and for the companionship intended by marriage to be achieved. If he spends the night outside the home without a valid excuse, thereby causing you harm, then he is not permitted to do so, as this does not fall under "living together in kindness" (al-mu'ashara bi'l-ma'ruf). Advise him to stop spending nights outside the home and alert him to the disapproval of staying up late without a valid purpose, as it is prohibited. Help him utilize his time in what benefits him religiously and worldly, and encourage him to attend circles of knowledge and associate with righteous people, while you, too, are a good wife to him.