Well, I won't agree with you less on what you've said, experience they say is a good teacher but comforting words do not need someone who has gone through such experience because no one wants to sit and watch his or her friend go through pains without saying something maybe we most times have to know how to comfort them but it does not necessarily mean we have to go through the experience. Even Scripture says, comfort those who mourn, there was no exception to who can comfort them but we can learn to say the right words when comforting them.
Secondly, some people may not have gone through marriages or relationships experiences or whatever but they've got the knowledge to advise those who need it. Most times they have this knowledge through reading, seeing things with their eyes, hearing, or perhaps the holy spirit.
Knowledge or perhaps discernment can be given to anyone to help a person in need regardless of their experience and it is left for those who are advising to know how to say it and left for us to fetch out what we want and discard what we don't accept.
Let's not forget that even the happily married couples' advice may not be the best for us because they looked for what works for them and stocked to it. Most times, what works for them may not be the best for us or may never work for us because we are not married to the same personality even though it is the same gender.
Know what you want, know what works for you and lastly, let's not forget to always pray because the only person that can give the best marital and relationship advice and comfort us is no other person but God in His word.
It was great reading your article.