Partner said we'd get married if he got new job, then turned the job down.

[Taurini]

So me and my partner have been together for 6 years, we live together and have a child together and we have been engaged for 4 years.. I have always said I'd be happy to just get married at a registry office and when we're older renew our vows and have a huge party etc.. but my boyfriend has always said no, he wants to do the whole big wedding thing and treat me like the princess he thinks i am.. we've been to 3 other people's weddings and he was always saying how ours would be better etc etc.. anyways.. he applied for a new job recently and the financial increase would have made a big difference in our lives.. he said to me that If he gets the job we would get married.. 2 interviews later, he gets offered the job and he decided he didn't want to take it as he wouldn't be able to work from home as much and the drive would take too much out of his free time (it's 10 mins longer than where he currently works) he'd have to give up his gym time or running time etc and he wants a good work/life balance.. which I totally understand..
But am I in the wrong for being upset? After all these years I got ideas in my head and got a little excited and I thought it was finally happening and now it's not..
He said we can go to the registry office if I want & said about having a celebration where if people want to attend they can pay for their meal.. he now wants to spend as little as possible as he thinks it's just a lot of money for one day..
It just feels like he's lost all motivation..he used to be the most motivated person I've ever known, he wanted something, he got it.. but now it feels like he has it good so changed his mind about the effort?
I know I probably shouldn't take it so personally but I cant help thinking he's loosing Interest in me.

Would it motivate him if you made it absolutely clear that you were losing interest in him?

You're clearly no longer a princess in his eyes! Sounds like he can't be arsed with anything other than his own needs.

What's he like otherwise in the relationship? As a father, a partner, with housework?

I would absolutely take it personally.

Has he made any plans towards this grand wedding he wants? Any savings ?

His actions to me say that he is not interested in marrying you. He doesn’t sound like he would make you a good husband. He’s not interested in what you want ie marriage now at a registry office or in coming to a compromise or coming up with a plan. I’d cut my losses now and move out

Does it financially benefit you to be married? If so, book the registry office. If not, then it is quite possibly time to look for a flat to move out to with your child. do you get the equivalent of his gym and me time? Does he pull his weight?

He is very supportive if I am honest, I have 2 children from a previous relationship who's father decided to leave when I was pregnant with the second and even though I have 2 children and health problems that leave me unable to work he took us on and looks after us without a complaint.
I take care of the house and children & cook their tea etc and he cooks our tea.
He gets up at 5am and leaves at 6am to go to the gym before work, occasionally he will meet with a friend for a run after work.
But saying that, if I've been up for dozens of nights in a row with our little one or I am sick and I have to ask him to stay home and help he does get grumpy and I end up feeling bad for asking because he works so hard for us.
& no I don't go out, I feel that because I can't work it'd be selfish of me to go out and have me time leaving him with the kids when he's been working all day.

I was honest at the start of our relationship about my health etc and told him to really think about it before he decides what he wants but he was completely unphased, within a couple of months he'd moved closer to spend more time with us and withing a couple of years we started living together as a blended family and he straight away decided he needed more money to support us and went and got a better job and then a bigger car etc.. then we had a baby.. and now it feels like he's bored or something

He does sound like a great guy, maybe he’s decided that you guys as a family will be better off not spending lots of money on a wedding. I know it’s something he mentioned about having a big wedding to begin with, have you spoken to him on the change of idea in what kind of a wedding he wanted to give you? My partner and I spoke about getting married in Italy before on a vineyard, with his family and my family, then after covid and the rising cost of living plus a toddler, we literally sack that idea off and haven’t really thought about what we wanted to do now.

Are you even sure gay marrying him would solve your relationship problems?