I have a cousin that says it’s imposible to come back to be friend of who has been your couple or any kind of significant other.
He affirms after you have been dating the frienship’s border can’t be marked again. I agree with him but I have to clarify my position.
Sometimes it’s possible to have a good and new relationship with that person was your couple if he/she has very clear doesn’t want anymore with you at emotional level, but if wants to have a second chance in the near or the far future that kind of relationship it’s a trouble. It depends on the people’s nature. If who you have to your side is someone only wants to have a pure, real and sane link with her /his past it’s ok but if it wants is to have a back up just in case, that isn’t a good scenario to try a positive post-romance relationship.
Sometimes people only are scared to be alone and that’s why try to have a lot of other people near of them, but sometimes too you must be egotistic to conserve your bliss point although people want to be with you to their benefit without a negative intention.