It is permissible to eat individually as well as eating together. However, eating together is better as it is a means of barakah.
عن وحشي رضي الله عنه أنهم قالوا يا رسول الله إنا نأكل ولا نشبع. قال فلعلكم تأكلون متفرقين؟ قالوا نعم. قال فاجتمعوا على طعامكم واذكروا اسم الله عليه يبارك لكم فيه. (ابن ماجة رقم 3286)
Hazrat Wahshi (Radhiyallahu Anhu) reports that the Sahaabah (Radhiyallahu Anhum) once complained to Rasulullah (Sallallahu Alaihi Wasallam): “O Rasulullah (Sallallahu Alaihi Wasallam), we eat but do not feel satisfied.” Rasulullah (Sallallahu Alaihi Wasallam) asked: “Perhaps you are eating individually?” The Sahaabah (Radhiyallahu Anhum) replied in the affirmative. Rasulullah (Sallallahu Alaihi Wasallam) advised them saying: “Eat together and take the name of Allah Ta’ala at the time of eating, Allah Ta’ala will place barakah in your food.”