When a friend of yours gets into a new relationship, or maybe has problems with a current relationship, it's tempting to give advice. And don't get me wrong, it's wonderful to give advice. It shows you care about that person's happiness and you want the best for them. But that's where the problem lies—do you know what's best for that person?
If you're not in the relationship, you have no way of knowing exactly how strong it is, what problems there are, and how bad each problem is. So any advice you give is really based on your best guess. Sure there are general pieces of advice that work for most people, so it is safe to assume it could work for them, but even then not all wisdom applies to every couple.
Every couple is different because every person is different.
Everyone has his/her own unique mixture of what makes them happy and what they want in a significant other. Cosmo magazine and Buzzfeed news would like you to believe that there are only five different kinds of people or three different kinds of couples and so on. There is literally a Buzzfeed video called "The 7 Types of Girls You Date." Really? Only seven types of girls in the world that you could date?
Since every person is different, and every couple is different...
Every relationship and how it should be handled is different. Sometimes couples decide to handle their issues in ways you would never think to. Sometimes couples work through enormous issues, and sometimes the seemingly tiny issues break them apart. It's always good for the couple to get outside opinions and see other options for keeping their happiness. They may even take the suggestion. Just don't expect them to.
I've noticed many people get confused or mad when they give advice one way and the couple doesn't follow it.
It's understandable to be confused in this scenario, especially if one or both of the people come directly to you for the advice. But when they come for advice, think of it less as "they want me to solve their problem" and more as "they want another suggestion so they know their options." It can be dangerous to expect someone to take your advice because then you're getting even more involved in a problem that isn't yours.
I'm not telling you to never give relationship advice. But I am suggesting you think about what you say.
Giving advice is a wonderful thing, of course, as long as it's done with the best of intentions. However, it's very important that if you choose to give advice, you remember that it's still up to the couple to make the decisions. Remind the person/people you're speaking with that this is just your own suggestion and it is up to them what will make them happiest.
You're welcome to give any and all suggestions you think could be helpful, just keep in mind that as individuals and as a couple they are unique. Their problems are unique, and their solutions can be, too.