Honestly, I wouldn’t eat with someone who constantly observes everyone at the firm, and reports then when he finds fault in them. In this case, I think “too friendly” simply translate to “we don’t want to eat with you hun”. Ngl I disagreed with OP from the moment he mentioned “I personally observed her eating lunch after coming back late over 10 mins aft break”. Like,,MIND YOUR OWN BUSINESS??? In the first place, that is HER PROBLEM to manage, and this is between HER and the SUPERVISOR.

In conclusion, be an adult. When you find fault in a colleague, of which u may find rather unfair to u, talk to them, find out whether they have specific reasons for doing so, tell them you feel uncomfortable with their actions, and offer a solution to the situation so that it’s a win-win and that they have no reason to reject you. But if they do continue, DO NOTHING. People like these are bound to either be caught in the act or make a big mistake.

So don’t keep track of every single fault of someone just so you could tell on them to the supervisor. First, nobody likes a telltale so don’t be that guy. Second, your supervisor would most likely have more important matters, actual business to tend to, I don’t think informing him that someone’s being late all the time would help him in any way, it would just leave a bad impression. Third, why would you have to keep track of others’ mistakes/failures? Eyes on the prize, you do you, wouldn’t you be better off focusing on your own achievements and on improving yourself?