Maybe it depends on what you are looking for out of the relationship.
If you are looking for someone to spend your life with, get married, have kids, and all that wonderful stuff (if it still exist), then I wouldn't do it with someone that was dating other people while I was dating them.
We are not courses at a buffet. You can't just pick up 5 to figure out which one is the best. Dating and life are much more complex than that.
But if you are just looking to have fun, then why not? I don't see a problem with it as long as you are up front about it being just for fun, and no plans to make it long-term for the immediate future.
If you are looking for someone to spend your life with, get married, have kids, and all that wonderful stuff (if it still exist), then I wouldn't do it with someone that was dating other people while I was dating them.
We are not courses at a buffet. You can't just pick up 5 to figure out which one is the best. Dating and life are much more complex than that.
But if you are just looking to have fun, then why not? I don't see a problem with it as long as you are up front about it being just for fun, and no plans to make it long-term for the immediate future.