The Value of Relationships, past and present

Relationships are interesting connections that you have with people - particularly ones where you are physically involved.
Is there a right or wrong answer as to whether it's okay to stay friends with someone you once dated?

Even if you broke up with someone over 10 years ago you can still have a close affiliation or admiration for them.... so too, someone you may have broken up with less than a year ago.
Is it possible to genuinely have a friendship afterwards (and no thoughts at all of ever wanting to get back with them)?

Depending on how you split, these post-relationship friendships can be harder than others.
When one party has another partner it can be a lot easier or even a lot harder...
Another factor is how much time has passed since the split.

It's vital that both people no longer have the same feelings for each other and that any break-up grudges have subsided.

Yet, it's okay to admire them and recognise that you do have a history with this person.

Out of my past relationships there are only two men that I am still in contact with and call my friends.
Is this wrong that I value their friendship and want them to still be in my life?
I know it's purely plutonic but is it not okay to see them if I am dating someone else?
How would I feel if my partner was friends with his exes?

Relationships involve trust... and if you can't trust your partner then you are with the wrong person!
I value the friendships I share with my exes, but is it not right for us to be friends?
I know nothing would ever happen between us again but does my partner truly know that too? And do I genuinely believe the reverse?

It's an interesting conversation I have had with many girlfriends previously... I know people from the dark ages (ie our parents) disagree, but how do people from my generation see it?

Comments welcome...