Max M. answered 08/27/19
Harvard Literature major with 20 years of coaching writers
I'm afraid your colleague wins your *debate.*
The difference has nothing to do with the actual meaning of the verbs. The simplest way I know of to describe the predicate verb is that it's the one that's actually happening in the sentence. In this sentence, is loving happening, or dressing up? It's the loving.
The verb form that starts with "to" in English is the infinitive, which is never the predicate verb. It's the form of the verb with no subject, so by definition, no one is doing it.