If its not cheating or an emotional affair, what is it?

[ImFeelingOuch]

Partner has a friend of the opposite sex. They talk a lot mostly about, day to day and common interests. However, they are often flirting as well, more so from the friend but my partner does engage with the flirting. This makes me uncomfortable and anxious. I have shared my feelings but have always been told they enjoy their friendship and it’s nothing more than that. I feel there is more to it but can’t put my finger on it. I don’t think it is an emotional affair as they don’t talk about emotions or wanting to be together, want and desires ect (or is it?). I’m confident it isn’t a physical affair so what is it?
What do I do?

Maybe it's a friendship? If it makes you uncomfortable and you can't get past it you need to split.

Sounds like banter and maybe the reason you're uncomfortable is that they are more comfortable with eachother than your DP is with you? Like you're secondbest?

Regardless, hurt feelings are very difficult to deal with and if you're feeling left out, action is probably required. If you made him choose, what would you think might happen?

Just because they don't talk about emotions doesn't mean they don't have feelings for each other.

If they are flirting there is obviously sexual attraction between them, even if she is more into your partner than he appears to be. The fact he is not shutting the flirtation down means he is encouraging her.

I think you are right to be concerned.

You need to talk to your partner. Ask him why, if they are " just friends" they are flirting with each other because platonic friendship doesn't include flirting. Ask him to put some boundaries in his friendship with her that are appropriate for someone in a relationship. If he won't do that and puts his " friendship" above your feelings then you will know where you stand.

We’ve been together close to 15 years.
I think a label would help me decide what to do. At the minute the easiest solution is to leave her. But easy isn’t always the right thing or the best thing.

The OP wrote At the minute the easiest solution is to leave her.

I think the sexes of the individuals involved are relevant here. OP, your partner is female; what about you and the friend? If the friend is female what you're describing sounds like a lot of close female friendships. If the friend is male I might be a little more wary as men seem bit more prone to sexualising their friendships with women. That said, I have a male friend who pre-dates my 15-year marriage and we have a very close, jokey relationship that could probably come across a bit flirty to an outsider, but there is 0% sexual attraction on either side. It's just a by-product of a lot of shared history and a similar sense of humour. We're more like siblings than anything else.
Nobody on here can tell you what your partner and her friend feel for one another; we'll all be projecting our own experiences onto their friendship.

Flirting how? Can you give us some examples?

I have a fair few close mixed sex relationships and it sounds a bit like some of those. I label them as ‘friendship’ if you’d like a label. A bit of flirting is fine, eg if I’m feeling down about a bad date and my friend might say ‘I bet you looked amazing in your black dress though’, I think that’s fine, even though could be classed as flirty. Compliments/ banter/ boosting each others’ confidence between friends, whether same or opposite sex, is normal IMO.

As someone with platonic friends of the opposite sex, if there is flirting involved then it's not platonic. It's disrespectful to you, and clearly you need to say it's not on.

What does the flirting consist of? I had an ex who had very strong views around this

I just assumed from the initial post OP was in an opposite sex relationship.
Perhaps I was wrong just to assume that.
I'm a bit confused now about things but I think what I posted in my pp still stands what ever the sex of those involved but it might have been better if OP had been clearer in the initial post.

Thank you all.
For clarity. I am male in an opposite sex relationship. My partners “friend” is male.

Define flirting as it means different things to different people. I have banter with friends of both sexes that includes sexual innuendo, but my partner is the same and we both know its meaningless.

It might be that you have different humour or boundaries or you could be right and it's an issue. The best thing to do is talk to your partner calmly and share your concerns / ask for reassurance

I'd call it an ego boost and a back up plan. She's keeping up this friendship in this manner because she enjoys the attention (ego boost) and if your relationship doesn't work out she's always got a back up plan.