[mk89]

I have seen places where people don't have any reason except for "naaa, I don't wanna spend my time with them, I prefer to spend it alone".

When there is a justification that goes beyond that, for me it's okay - actually, I am okay with every decision.

However, I have seen places where people create real factions during lunch time, or they just tend to be alone, because of the reason mentioned above.

No criticism, just an observation, which is wrong apparently, if not all factors (different schedules, etc.) are taken into account. :)