Why is it so hard to talk to an ex-boyfriend or ex-girlfriend?

In my persona experience the fact that you used to be so close with someone (exboyfriend or girlfriend) makes it way harder to set up new boundaries or the simple fact of you having to accept that the relationship its over while you still have feelings for that person can make it way harder than it should be.

Because of the feelings lost. It could be painful because of all the good memory's overpowering the senses so it becomes scary to repress the emotions from someone once loved.

It is hard to talk to them because you once loved them. You may still love them and they just don't know it.

Talking to people from your past that you were emotionally invested in is difficult because it stirs up those old emotions and opens Old Wounds

It is so hard to talk to an ex because he or she had such a big role in your life and then they just disappeared. It is natural to feel as though you have lost part of you for this reason

I think it's because of the past you shared with that person. Usually there are good moments even in a bad relationship which can lead to conflicting feelings regarding that person.

Why is it so hard to talk to an ex-boyfriend or girlfriend? Well for starters, some people are just not easy to talk to. Maybe there are still some unresolved issues that need closure and with time maybe it will become easier to have a cordial conversation .

Many reasons may be attributed. The damage that has happened between you and ex that lead to breakup might be huge that you believe you can't even talk to them. It could be your ego preventing you from talking to your ex. It might be the fear of their reaction and rejection. You might be reflecting your past experiences with your ex into the future thinking talking to them will lead more troubles. You might be hurt so much that you can't talk to them anymore.

There is a big difference between friend and partner, and this radical difference makes it hard to interact with said person when you go from lovers to friends, perhaps due to things you knew by being their partner or because of how the acted around you when there was still a relationship

For me it was difficult to remember that we no longer had that type of relationship. So there is that stress of remembering the new boundaries. Undoing late night talks, nicknames, and saying I love you after every meeting. It can be utterly awkward. With sometime you can decide whether or not if it's right for you to continue talking with them or if you'd rather move on.