So went a noun ends in ה, it is replaced with a ת + ending? Just clarifying as it isn't mentioned in the tips and notes
האהבה שלו - אהבתו
האהבה שלה - אהבתה
האהבה שלהם/ן - אהבתם/ן
האהבה שלכם/ן - אהבתכם/ן
האהבה שלנו - אהבתינו
That's right. It also happens in the construct state - מסעדת הפסטה (the pasta restaurant). Compare to ta marbuta in Arabic.
I know that this form, with the suffixed endings for possession, is common for body parts or family members. However, with מסעדה, does this sound natural to native speakers, or does it sound stilted to use this form? Other words where it's common to use the suffixed endings?
The word מסעדתו indeed sounds awkward. Most words do with a possesive suffix. All I could think of that everyone uses is אחותי, my sister. Except that, informal native Hebrew hardly puts these suffixes in conversation
What would the Hebrew be if you wanted to say 'he closes his restaurants'?
I don't know if it's correct, I'm learning too, but Reverso has it as: מסעדותיו
It should be מִסְעֲדָתוֹ [mis'adato]. [-at] was the old feminine ending for nouns, and the [t] was lost, when standing at the end in the base form of the noun, but the [a] was retained, therefore the vowel does not change between the status absolutus and its suffixed form.