I hate when people say that it’s really weird for you to be friends with your ex. I don’t see why you cannot be cool with your ex, just because your relationship is over.
Unless the relationship ends badly or one of you is still feeling the other individual, then there is nothing wrong with remaining in contact with them.
I am friends with all of the exes that I am still in contact with and it’s all good. We still have conversations, I check up on them, they check up on me and we show each other the love.
Part of the reason I have remained friends with my exes is that we were friends in the first place, so why should we not be friends after our relationship has ended.
Being friends with your exes can be perfectly innocent and it should not be seen as such a huge problem. At the end of the day, when getting into a new relationship, the two of you should trust each other, so you’ll know that their friendship with their ex is not an issue. Being friends with an ex simply does not bother me.