(Picture: metro/co.uk

When a parent dates someone closer to your age than theirs, things can feel awkward. But this week’s reader has even more reason to be feel uncomfortable.

The 21-year-old got in touch because his dad’s girlfriend, in her late twenties, keeps flirting with him. The most inappropriate part? She keeps ‘accidentally’ walking in on him naked.

Should he tell his father?

Read on for the advice, and before you go, check out last week’s dilemma, where a man found out his girlfriend had faked her entire identity.

The problem…

How do I tell my dad that his girlfriend keeps flirting with me? He adores her and I don’t want to break his heart, but the situation is becoming impossible.

Mum left home when me and my sister were young, and we haven’t seen much of her since. Dad was great while we were growing up, but now we’re both adults, he has decided that at 45 he needs to devote some time to himself.

He met this woman at a gym he started going to, so she is quite fit in all senses of the word. She’s in her late twenties, I’m 21, so she is a lot nearer my age than his.

She hasn’t moved in but is always at our house and has a lot of stuff there. We only have one bathroom, which doesn’t have a lock, as it’s obvious when someone’s in there. But more than once she has wandered in ‘accidentally’ to get something while I’m having a soak, and as if it isn’t bad enough for her to nip in and out again, she stays and chats as though it’s all perfectly normal.

She frequently compliments me on the way I look, touches me in inappropriate ways, and recently said to me that if she often wonders if she picked the right bloke.

I’ve tried to tell Dad I’m not keen on her, but he thinks it’s just jealousy because we had him to ourselves growing up.

What do I do?

The answer…

Well, apart from the obvious ‘get a lock on the bathroom door’, it’s clear you’re in a difficult situation. I can imagine how much love and loyalty you have to your dad, who after all has brought you up almost on his own.

Our family expert, Dr Hari Rudkin, says that while you have no control over the behaviour of his girlfriend, you do have control over how you respond to the situation.

‘Have an honest chat with her’ she says. ‘Be very clear that you’re not attracted to her (even if this involves a lie) so she knows where the boundaries are. Right now, she’s creating a very blurry boundary, treating you as a potential boyfriend rather than the child of her partner.’

It might be a difficult conversation, but you need to let her know that you’ll have to tell your father if the situation continues.

‘If it does reach the point where you have to tell your dad, accept that initially he may well be annoyed and defensive.’ says Dr Rudkin. ‘Nevertheless, I can guarantee that he would rather know that not.’

Dr Rudkin thinks it might be easier having your sister there if you end up having that tricky chat with your dad.

Meanwhile, stay out of his girlfriend’s way and avoid too much interaction with her. Hopefully, she’ll get the hint that you’re not interested.

As to whether her relationship with your dad has a happy ending, best leave it to them to sort out.

Dr Angharad Rudkin is a clinical psychologist and co-author of What’s My Child Thinking and The Split Survival Kit.

MORE : ‘My girlfriend faked her entire identity – including lies about her ‘dead’ parents’

‘ve tried to tell Dad I’m not keen on her, but he thinks it’s just jealousy.’