Hey Alex)) The original word is معلموي which is considered phonetically inappropriate (The encounter of the long vowel و and ياء المتكلم). The واو الجماعة is elated here to facilitate pronunciation. The و would be retained with other suffixed pronouns, given they aren't vowels: معلموه، معلموك، معلمونا،... Taking another word like مساعِدون helpers - My helpers = مُساعدِيَّ not مساعدوي Two long vowels cannot meet in words - The vowel letter themselves nonetheless ألف، واو، ياء can do so, as long as both of them have SHORT vowels (الكُوَيْت Kuwait - notice the diacritics) or one of them AT MOST is a long vowel (معلِّماي my two teachers, وَلدايَ my two sons, يحتَوي contains) Hope this helps!

In Arabic, the construct state (الإضافة) is used to show possession, ownership, or relationship between two nouns. The construct state is formed by combining two nouns, where the first noun is in the genitive case (مجرور), and the second noun is in the nominative case (مرفوع). When the first noun ends with the vowel "a" (fatḥah), the conjunction "wa" (و) is added between the two nouns. However, when the first noun ends with the letter "n" (ن), the conjunction "wa" is dropped. Therefore, in the case of "my teachers," the possessive pronoun "my" is attached to the first noun "teachers," which is in the genitive case. Since "teachers" ends with the letter "n" (معلمين), the conjunction "wa" is dropped, and the construct state becomes "معلميَّ" (ma‘alimī) in the nominative case, indicating possession or ownership. So the reason why the conjunction "wa" is taken away in the construct state is due to the rules of Arabic grammar.

Thank you very much for your profound explanation. I understand that when we add a suffix pronoun the noun becomes in a form of idafa (إضافة). It is used without the definite article (ال). But I it shouldn't be in the genitive case. If we say "his teachers" - معلموه, it's used in the nominative case. Only the suffix pronoun "my" is always used like ي…ِ-. I'd like to know is there a rule about the use of long vowels for my case. Is it possible to use two long vowels in a row in Arabic?