Blended families can be beautiful things, but navigating bad behavior can be tricky with step siblings.

When this woman’s boyfriend kept acting strange around his stepsister but couldn’t see it, she decided to get creative.

You’re definitely going to want all of the details on this one.

AITA for acting like my boyfriend’s stepsister to prove a point?

My (27f) bf (26m) “Matt” and I have been together nearly four years, and moved in together earlier this year.

His stepsister “Clara” is currently staying with us for a few weeks on and off and that’s where the problem arises.

Clara has always been a “princess” type. That’s her thing, whatever.

But it’s always annoyed me how Matt reacts to it.

Uh oh, a few weeks with a princess? There’s bound to be drama.

He goes along with it completely.

He is her doormat from the second she arrives until the second she leaves.

I always figured that’s his choice and his business, so I never said anything about it. But since she’s been staying it’s really been bothering me.

He carries her things like a pack mule, runs around every morning trying to get her the breakfast she wants, makes reservations at restaurants he hates just because she likes it, and gives her free use of his credit cards to buy whatever she wants.

There’s other things but these are the type of things.

Whoa, why the special service?

I feel so awkward when he’s fawning over her like that.

I’ve spoken to him about how he acts around her and his excuse is always “what am I supposed to do, that’s how she is.”

I asked him if he doesn’t find it inconsiderate and annoying, and he said no.

I don’t believe him. I don’t believe he could not notice that the way she acts is inconsiderate.

So I tried an experiment. I started acting like her.

This is actually a brilliant social experiment.

Last week, the last day she was here, I said I wanted fresh fruit for breakfast.

When Matt didn’t say anything, I asked if he’d go get some, which he did.

When we went out for lunch, I didn’t even offer to pay.

When we went to run errands after lunch I made him drive 30 minutes to the next town over to go to a particular shopping centre, and I took longer than usual choosing products.

I also made him drive home.

Ok, wow, this is major diva behavior.

I could see he was a bit annoyed by me but he didn’t say anything.

Later, I suggested we order take out instead of cooking and when he said “Ok,” I asked to order on his app.

Clara got home after we ate, and Matt spent most of the evening playing video games with her because he was clearly upset with me by this time.

After she went to bed, Matt confronted me, asking if I was ok because I had been acting odd all day.

Hm, or perhaps, she was doing an impersonation of someone…

He said I’d been treating him like he works for me which he didn’t appreciate, but if I was stressed or upset we should talk through it.

I told him that I had spent one day treating him exactly how his sister does, and he hated it, so he can’t say he doesn’t notice how she is.

Maybe he’ll finally realize what she’s been saying.

Matt got mad and said that was an insane thing to do, and he noticed because that’s not my personality.

He called me childish and said I’d wasted a day for nothing.

It’s been a few days and things have been awkward.

Matt has been spending evenings gaming or with friends and has been cold to me.

Oof, that didn’t go smoothly.

I don’t think I did anything that bad but my girlfriends say testing him like that was stupid when Matt treating Clara like a baby really doesn’t affect me, so I should just ignore it.

Now I feel bad.

Nobody seems to understand this girlfriend’s gripes.

Will Reddit? Let’s see what the commenters have to say.

First up, a Redditor chimes in their support but notes the “weirdness.”

Next, a user mentions the unspeakable.

Quite a few think there is an attraction between these stepsiblings.

Finally, a reader notes how Matt enables Clara’s bad behavior.

Matt’s relationship with his girlfriend needs to come first.

If she feels uncomfortable, he should listen to that.

If you liked that story, check out this post about a group of employees who got together and why working from home was a good financial decision.