Is this correct?
Even though the subject/verb is never part of a prepositional phrase, the object of the preposition influences the verb?
Example Some of the houses were red Some of the house was red.
Is this correct?
Even though the subject/verb is never part of a prepositional phrase, the object of the preposition influences the verb?
Example Some of the houses were red Some of the house was red.
No. At least, not directly.
The prepositional phrase is an optional part of the sentence. The noun and verb should always agree, and the preposition does not affect that. You should be able to completely remove a prepositional phrase and have the sentence remain fine, at least grammatically.
What the object of a preposition does affect is the noun/pronoun.
Your example is tricky, because "some" is a pronoun that can be singular or plural. If you use "many" and "much" instead, you would have "Many of the houses were red," and "Much of the house was red."
"Many were red" works, "Much were red" does not.
"Many was red" is painfully incorrect, but "Much was red" is correct.
Choose the correct pronoun based on the object of the preposition. Then, choose the verb based on the pronoun–whether it's singular, or plural.