In Finnish colloquial language 'se' may refer both to a person or to a thing. Logically 'se' in the sentences 'se oli työkaveri' and 'No ei se kyllä siltä näyttänyt' should refer to the same object (apparently a man). By common sense, either, the object of 'se' in the last sentence is different, that is, the situation as a whole. It is difficult to imagine that you can tell a colleague (or non-colleague) by his look, but you can tell it by the behaviour. Apparently, the couple was embracing and "colleage" presumably was her lover.