I can’t shake this horrible feeling about my boyfriend and his sister

DEAR DEIDRE: I’ve got a horrible feeling that my boyfriend is in a sexual relationship with his sister.

There’s something off about the way they act with each other – too touchy, feely and even flirty.

I’m 26, he’s 28 and we’ve been in a relationship for six months. His sister is 27.

My boyfriend and his sister share a flat and whenever I go round they’re always laughing and making cheeky, sometimes sexual, remarks to each other. It’s really inappropriate.

Last week, he had some tight jeans on, and she made a joke about his big bulge.

They sit dead close on the sofa, and when they hug it’s too tight and for too long. Worse, when he looks at her, he gets the same look in his eyes that he gets when he looks at me.

They act like they’re sleeping together – to the extent that once I sneaked into her bedroom to check if her bed had been slept in. It had been.

I know you’ll just say I’m jealous, and insecure, but I think there’s more going on. I’m starting to feel really disturbed about it. I don’t want to go round to his place any more. What should I do?

DEIDRE SAYS: All families are different, and it may be that your boyfriend’s is just unusually affectionate and tactile.

Incest is illegal, so if they were sleeping together, it’s very unlikely they would be acting like this in front of you. It’s more likely they’re just very close and have always made sexual jokes.

But this is upsetting you, so say something to your boyfriend. Perhaps you could tell him how uncomfortable their behaviour makes you, and say it feels inappropriate.

My support pack, Standing Up For Yourself, should help you to have this chat. If you’re really worried, speak to Family Action in confidence (family-action.org.uk, 0808 802 6666).