“Bridgerton” fans are here for Penelope Featherington and Colin Bridgerton’s blossoming romance — especially after watching the much-anticipated mirror sex scene. But let’s not forget about how their love story impacts Eloise Bridgerton, Colin’s sister who also happens to be Penelope’s best friend.

Although Penelope and Eloise’s friendship starts off a bit rocky in season three, the two have been close ever since they were little. The fact that they were best friends long before Colin entered the picture has many viewers wondering if Penelope broke “girl code” by pursuing her best friend’s brother.

Interestingly enough, this isn’t the only complicated relationship/friend dynamic in the series, though. Lord Marcus, Lady Danbury’s brother, also pursues Violet Bridgerton, Lady Danbury’s good friend. (The two of them became very close during season one when they were matchmaking Simon and Daphne.) Upon realizing that her brother had romantic interest in her good friend, Lady Danbury says in episode six, “It is not for you to go after my friend” and “must you take everything from me?”

“Anything you do with a friend’s sibling will change your relationship with your friend somewhat, so you are taking a risk in pursuing their sibling,” relationship expert Nicole Moore says. “As such, it’s best to only take that risk if you really believe it will lead to something truly good long-term.”

Obviously viewers want Polin (the couple name given to Penelope and Colin) and Lady Danbury and Lord Marcus to be end game, but at what cost to their friendships? Below, Moore shares her opinion on whether it’s OK to date, marry, or get finger-banged by your best friend’s brother in the back of a carriage.

Is Dating Your Friend’s Sibling Fair Game?

When it comes to “girl code,” the only thing that’s not fair game is dating someone who your friend is dating or who has dated in the past, Moore says. (And even then, there are some exceptions.) If your friend has a healthy relationship with their sibling, it’s absolutely fair game. “It would be unfair of your friend to keep you from dating their sibling just because of their own feelings,” Moore confirms.

Of course, there are exceptions, like if your friend has a problematic relationship with their sibling or if they’ve caused them harm. Those may be examples where you wouldn’t want to date your friend’s sibling out of respect for your friend, Moore says. But generally speaking, dating a friend’s sibling doesn’t have to be weird.

“When we question if it’s OK to date a friend’s sibling, we’re really asking if it’s OK to potentially upset a friend,” Moore says. And while it’s not your friend’s decision whether you should or shouldn’t pursue their sibling, it comes down to “how much you believe you should take other’s feelings into account when making personal decisions,” Moore adds.

How to Pursue and Date Your Friend’s Sibling (Respectfully)

It would be respectful to give your friend a heads up if you’re into their sibling. You don’t necessarily need to ask for permission though, Moore says. “A sibling is not the owner of their other sibling, and they don’t get to keep you away from potential romantic partners simply because it might feel uncomfortable for them to have a friend date their sibling.” Let your friend know you’d like to pursue their sibling without asking for permission, Moore reiterates.

Once you tell your friend, understand that your friend may not take it well. “They may fear losing closeness with you or becoming the third wheel,” Moore adds. If this happens, it’s best to reassure your friend that your relationship with them will remain solid. If they start listing off reasons why it would not be a good idea to pursue their sibling, “listen to their feedback respectfully knowing their intention is good,” Moore says. It’s up to you whether you decide to pursue their sibling afterward.

On the other hand, your friend may get super excited and start projecting your futures together. This is a positive reaction, but know that you may have to set boundaries later if your friend involves themselves too much in your relationship.

Ultimately, it’s up to you who you pursue romantically, and you shouldn’t prevent yourself from finding love even if it is with your friend’s sibling. “If you truly feel their sibling might be a romantic match long-term, pursue it after you’ve had a conversation with your friend about it first,” Moore says.