English grammar rule Comma compound sentence
I thought you and he was happy.
When personal pronouns serve as subjects of a sentence or clause, they are in the first (I, we), second (you), or third person (he, she, it, they). They also are either singular (I, you, he, she, it) or plural (we, you, they). You must use the verb form that corresponds with your pronoun in the same sentence.
Incorrect They loves a white beach. Correct They love a white beach. Incorrect He enjoy dinner when it come to the table. Correct He enjoys dinner when it comes to the table.