Complex sentence: Humbert becomes very possessive and strict, forbidding Lolita to take part in after-school activities or to associate with boys; most of the townspeople, however, see this as the action of a loving and concerned, while old-fashioned, parent.
Split into simpler sentences: Humbert becomes very possessive and strict, forbidding Lolita to take part in after-school activities or to associate with boys. However, most of the townspeople see this as the action of a loving and concerned, though old-fashioned, parent.