To not socialise with my colleagues.....I'm the manager.

This

If they want a night out then they should organise a night out.

It's not your job to facilitate their social lives.

I haven't socialised with line reports ever since I became a manager. It's just not appropriate.

You can be friendly but you are not their friends.

This.
I'm public sector, and we tend to go for a meal at some point in lieu of Christmas, and then if someone is leaving the team.
It isn't down to the Manager to arrange it though - one of the team volunteers.

I would have a team event/team night out. Just suggest that you have a regular get together maybe once a quarter and ask for suggestions- you don't have to be the one organising it but you should go tbh.
I tend to think of them as part of work rather than something out of choice - its part of building team spirit /morale.
We tend to do things as more of a department rather than team which makes it easier as its bigger and would include people i don't directly manage (as well as people on my level)- is that an option?

As an NHS manager though I don't think the onus is on you to organise nights out/pay for drinks or co-ordinate the social aspect of work. I appreciate this is different in the private sector. I would rather have a supportive manager who was flexible and empathetic when necessary.

Interesting question

My manager actively avoids all socialising outside of work and to be honest I find it a bit rude

Yes, I get it that he thinks we might want to occasionally let off steam and chat without him there (which is why he doesn't join is), but instead I just get the impression he's not interested in us people

We are a really close team but a bit bigger
Usually we do with manager

Christmas work do (manager comes to the meal and leaves before the bar crawl starts!)
The odd "it's sunny, let's have a pint after work, I will pay" where he will come for one drink and pay for the first round
Then probably every 4 months or so we have a team pub meal straight after work

Outside of that we have smaller groups of us that socialise separately without manager

I think it depends on what the expectation is. If they want to do something every week, or even every month, then YANBU, but if it's a couple of times a year (perhaps after an away day, or a meal and drinks at Christmas), then I think you are being a bit dickish.

I've previously managed two similar sized teams in the NHS - in one, we'd go out for a Christmas meal and to celebrate significant life events - big birthdays, going on maternity leave etc - usually a meal after work. In the other team we tended to go and do an activity we all enjoyed together 3 or 4 times a year at a weekend - e.g. bowling and lunch.

Your manager is my spirit animal 🙌🏼
"My family life is so very busy that unfortunately I won't be able to make it, such a shame, I really never wanted to go, I've got (insert excuse of the day here)", etc, etc. I work as admin in a NHS clinical team as well and wild horses can't make me socialise with colleagues outside the Christmas dinner.

OP, I'd suggest putting the ball back in their court. "OK Mary, why don't you discuss among yourselves what you would like to do, let me know and I'll book everything, shall I?". Then, approach the event exactly as above, arrive late because "you've got caught in a call" and leave early because (insert your favourite excuse) and wish everyone carry on having a good time before you leave. Like the PP said it above, people might see through it but it works well and they won't begrudge you for that

Nobody is going to leave a job that works for them because Kayleigh, Lisa and Fran go clubbing of a weekend without inviting everyone, or Debbie and Barbara do the odd theatre trip together without the whole team having to go

I disagree, there are plenty of threads on here when people have been nudged out or felt their colleagues are hanging together and getting closer leaving people out, talking about them, creating an atmosphere.

4 team members who are asking for a night out - to decompress, get to know each other better.

It doesn’t have to be a big night - just a couple of hours fun.

I agree with PP as a manager you need to be a people person and put your staff first.

If there are only 4 of you, surely it can't be too difficult to ask them what they want to do ?
Plenty of people can get on well with colleagues without have to socialise with them too.
It will depend on childcare (if needed), travel, budget, and, to some extent, personality.

I think there are ways as a manager to do this while keeping boundaries.

You arrange the drinks/dinner whatever buy a round or two and then bow out after a time. It’s the best of all worlds.

It’s not really about you though is it? If you’ve been told it’s an issue than you need to address it. I don’t particularly like nights out with my boss either, however I do appreciate the gesture. A few polite words here and there, boss generally departs early and the team can carry on as they want.
Dont be a manager that forgets their people are their most valuable asset. I never really understand managers who don’t seem to like working with people…I’m sure you can survive an hours drinks once every 3 months….

Not necessarily.
In all teams there will be people who want to go "out out" and people who don't want to go at all, and others who might come once a year to 'be seen to be going',, and others who would join in the local dart league but don't want to go off clubbing and others who would join a trip to a sports match but not want to just go drinking, etc etc.
Nobody is going to leave a job that works for them because Kayleigh, Lisa and Fran go clubbing of a weekend without inviting everyone, or Debbie and Barbara do the odd theatre trip together without the whole team having to go.

Clearly, everyone isn't going to be best buddies just because they work in the same team

I get on well with all my colleagues and they love going out and I hate it so I don't go. They always invite me and I decline. No excuses I just say no thanks and they accept it. We are still a!l friendly and work well together. Not sure how well we'd get on if they saw me pissed.
Anyway I don't think it's necessary.

The issue is, either you arrange it and invite everyone and give up an hour of your time, or they start to split into sub groups and exclude others / new team members, then you have a high staff turnover.

I do think an annual meal out can be quite nice (in lieu of a Christmas Meal maybe), but if some of your team want to be going out regularly, then it is for them to organise.

It can be a fine line for Managers to be socialising regularly with their Team - can make bringing up any performance issues you need to raise, difficult.

My manager arranges a night out once a year, occasionally twice a year which starts 15 mins or so after we finish work. He usually walks out the door bang on time but on these evenings he is always caught on a call and turns up about 20 mins late. He buys everyone a drink, chats for 30 mins and then, oh, it turns out that its parents' evening/his family are staying/something else has cropped up and he leaves.
We all see through it but it actually works quite well.

I used to manage a team but stepped down when I became a single parent.

I never wanted to do / organise things like this, even though I liked them as a team. However irrespective of whether I wanted to do it, I did it once every 3 months or so because I accepted that that's what teams wan in order to feel cohesive, appreciated and that they are all on the same team.

It has to come from someone who oversees them as you are the one who should be letting them know thAt they are valued, that you appreciate the work that they do and that's what motivates people.

You don't have to pay for it obviously (maybe one round or a small Contribution to the thing that you do)

But in my experience it's things like this that help a team remain a team. A couple of hours out of your day / evening a few times a year surely isn't that big a deal ?

Tricky one. Within my team there are kind of sub-groups of similar ages that do things together. However, occasionally (literally twice a year or so) we do organise something casual like a chilled out meal or a few drinks that does involve everyone. I'm quite happy with that, as I really like my team and we all do get on well. I'm very conscious not to have one too many gins, but we do have fun and I think it helps with the general camaraderie between us. It doesn't blur lines - in work, they know that essentially I'm in charge, but equally they know I always have their back both inside and outside of work. It seems to work well for us - at least, I hope so.
If I were in your position, I'd maybe pop along for a couple of drinks and then maybe leave it at that? It shows willing, but not giving too much of your time.