'I'm in love with my sister's fiancé. And she has no idea I'm pregnant with his baby.'

There’s nothing quite like the burning passion of forbidden love. And we’ve all been there.

Your older brother’s best friend. The ex of an acquaintance. A flirtatious workplace romance.

But as functioning members of society, there are some relationship lines we inherently know never to cross… yeah?

But the people of the Internet have taken to anonymous secret-sharing app, Whisper, to air some of their dirty laundry. Of the ‘I’m in love with my sibling’s partner’ variety.

For some, it’s a case of unrequited love, the kind that you never utter to a soul while it eats away at your insides.

“I’m in love with my sister’s boyfriend. I have been for years. I wish I wasn’t.”

For one person, their feelings evolved from friendship.

“My sister’s boyfriend is my best friend… I recently realised I’m in love with him.”

Then for others, comes the guilt of secretly wishing your sibling could get the heck out the way so you and their partner can walk happily into the sunset.

“I’m in love with my sister’s girlfriend. There doesn’t go a day that I wish she was with me instead.”

"I'm in love with my sister's boyfriend. The thing is, we talk all the time, and he says "love you sis". He says it in a brotherly way... I want so bad for it not to be brotherly."

Some Whisper users are convinced their sibling's partner likes them back.

"I'm in love with my sister's boyfriend... and he loves me."

One person is too afraid to make a move, even if the couple breaks up.

"I want to be with my sister's boyfriend. They are on the verge of breaking up, but I'm afraid to be with him next. I don't want to be a rebound."

And then there are the humans who appear to be savagely betraying their flesh and blood without a care in the world.

"I'm in love with my sister's boyfriend. We have been sleeping together for six months..."

"I'm in love with my brother's girlfriend, we've made out while he was in the shower."

(Mike Pence, US Vice President, has some verrrrry interesting rules about being seen with the opposite sex. Post continues after audio...)

Oh, and it gets worse...

"I slept with my brother's girlfriend. Shortly after she left him for a girl. I don't feel guilty, I love turning straight women."

"I purposely wear skimpy outfits when my sister's boyfriend is around.  I have a better body than my sister. I love how he looks at me and how jealous she gets." 

And there's this, which is really just too much.

"I'm in love with my sister's boyfriend. They're getting married tomorrow and nobody suspects that I am pregnant. From him."

All the best guys. Love's a bit sh*t sometimes, isn't it?

What do you think, is it ever okay to have, or act on feelings for a family member's partner?