It does say in pirkie avos “al tarbeh sicha im haesha”. Is there anything inherently wrong? Probably not, however, from what I have seen, conversations about shidduchim lead to much tangential converstion. And such a relationship between singles, without intention of any tachlis can lead to trouble (certainly can play on frustrations).
There is a much talked about concept of an “office wife” (not referring to any illicit behaviour), which defines a close office relationship that is not in synch with a Torah haskafah and gedarim that the chachamim have established, for those who are concerned with living with a Torah haskafah. Obviously not everyone considers such a haskafa important, but that is for you to consider.