To wonder if he’s hiding something?

Posting on your profile is very different to tagging him and telling everyone he knows. That’s going to prompt questions he’s probably not ready for after such a short time. I’m not surprised he didn’t consent to that and felt you massively overstepped.
I have approvals on so I can check/authorise it when anyone tags me. I think he needs that too.

Also, the soulmate comment is so cringe. And hardly a soulmate if he can’t talk to you about a preference and instead goes into a sulk! I’d get rid asap.

Ask him with all the detail you've given here. Ask him what's wrong when he sat next to you and okayed the post, and see what he says.

It’s only been 3 months
He’s split up from a presumably long term partner
You shouldn’t have posted/tagged without asking
He shouldn’t have gone sullen

or all three

love this economical response

forgot to say, what he is hiding is his irritation

the decision to ‘slow down’ is possibly out of your hands now that
you have attempted to broadcast your relationship to the world

even Rosamund Pike was dumped when she posted a hot tub picture
of her and her intended and sent to all friends, he was horrified and ended things
a week before the wedding

you misled him into thinking this picture would be on your page,
now it is out there
you should remove or hide it at least

Ask him about it. There's something else going on here.

Why did he tell you it was ok to post in the first place? Why would he worry about his ex seeing it?

I would wonder if he's trying to hide this from someone too. It really makes no sense that he would be ok with you uploading it then get mad. But when you tagged him, he became visible.

That said, he's love bombing you. Soulmate after a few weeks of dating, come on now.

Luckily me and dh aren't into posting out life online this would have made me annoyed to

I mean if this guy can’t communicate decently with you over this then it’s a bit shit isn’t it. Why couldn’t he just say ‘please don’t’ or ‘it’s ok just don’t tag me’ ??

There was no need for that post OP and I hope it doesn't cost you the relationship.

Social media relationship announcements are for teenagers. Not adults.

Grown adults posting selfies online is always going to be a bit cringe - I bet he didn’t mind the idea after a few drinks but woke up the next morning and felt embarrassed by it.

You told him you were going to post it, but did you tell him you were going to tag him?

DH (of 40 plus years) still checks first if he is going to tag me in anything. As someone else has pointed out, tagging him means that everyone he is friends with with see the picture. He may not have minded your friends/family seeing it, but posting it to all of his friends/family too is a bit much if he wasn't aware.

I would be furious if a partner of mine did that. I don’t like SM and thankfully nor does DH. We have never posted a single photo of either of us or DS online and never will. If others decided to do so we would make it clear that it needed to be removed.

Other than LinkedIn I don’t think there are any photos of the 3 of us anywhere online. Long may that continue.

I wouldn't want to be dragged into your attention seeking behaviour, so would be cross too. I'd probably knock the relationship on the head.

Trust the actions not the words.

No one can love someone within 12 weeks. How can he love you presumably just 5 months after he’s been saying he loves his ex? Hes throwing around words without truly meaning them. Like he wants to simply recreate what he’s just lost with his ex.

Taking things slow doesnt mean it wont grow into a lasting and loving relationship. It just means youre more likely to feel genuine love and the slow pace will allow you both to gradually grow in the relationship without all the drama that comes with rushing things and acting rather than meaning.

I don't think it's necessarily that "his words don't match his actions". It's normal for people to behave one way in private and not necessarily want that same side of them broadcast online for hundreds of strangers to see.

I agree. The assumption that everyone would be fine with having their photo and their location and who they’re with and what they’re doing all over Facebook is just awful.

That sounds very strange.

What strikes me is that it’s all very rushed. 20 weeks since you both split with others and only 12 weeks together and you’re in love? Like real love? No, sorry.

Sounds like you’re both playing at love but really you’re just dating and getting to know each other.

Slow things down. You have a kid in the mix - how do they feel about mum moving on so fast? I’m assuming they haven’t met him? For all your sakes, there’s no benefit of rushing in deep so quickly, take your time and keep your independence.

I would HATE for someone to do this as I don't even have SM myself. Being a private person this would have been too much for me. What is it with this obsession about showing the whole world your private life?

Yes but you tagged him in it so everyone who knows him saw it, rather than it just being your friends.
I don't think it's that odd that he doesn't want to upset his ex either tbh. It's pretty quick to be seeing someone else (not a criticism) but he might be worried about giving the wrong impression to her and others that there was an overlap perhaps.
Also how do you know about his ex going back to London? Did his mum tell you or did you see that on social media, too?