Am I damaging DP's career?

[Wintercoats]

DP has been working a job for the past 4 years, he works as a graphics designer for a small company, around an hour away. He's on less than 25k, works full-time, degree in graphic design. It costs him £250+ a month petrol to commute there, he works full on hours (leaves at 7:30 home at 8pm), and doesn't get paid any more for the hours he works.

They avoid giving him any kind of pay rise (eg last time invited him for an appraisal, asked him what he wanted to earn, he told them and then they said 'oh yes, we will definitely give you that in a years time', and he walked out empty handed...Again.)

They constantly ask him to stay late (his working hours are supposed to be 9-5 but there is a clause in contract so they can abuse this)

They can't retain ANY staff (every person hired in last 4 years has quit, minus DP and one other admin staff) so now they only hire free lance and bank staff.

They treat him awfully but then they flip it and make comments like ' we are only doing this because we know how good you are', 'we are only this harsh because we see such potential'

They always string him along with promises of promotion, shares on business, better pay.

So... I feel as if he is in an abusive relationship with his work and it's really getting me down. I'm so k of being home alone all night, with all responsibility falling on me. We are moving into our flat tomorrow, and DP is working, it's me taking time off AGAIN. He has now been asked to work Sunday/Monday/Christmas Eve while his boss goes on holiday. It's pushed me to breaking point and I am done. I feel so alone. Every time I try and talk to him he says I'm damaging his career, I'm being a nag, they're going to fire him if I kick up a fuss, I'm adding to his stress, this is not uncommon lots of work places are like this and I'm just being dramatic.... It goes on....

I need your advice and opinions, am I damaging his career by asking him to think about a new job, am I being unfair to say I can't stay in a relationship with this man if it goes on like this? I would like to ttc in the next year and there is no way I'm raising a child alone.

Thanks for all of the replies. I spoke to my DP, at first he was very annoyed and defensive, but eventually he admitted that he understood what I was saying and agreed with me that it isn't fair and the financial/work-life balance just isn't okay. He's agreed to sit down properly and talk it through with me, so we are on the same page.
Honestly I just think that his current boss has destroyed his self-esteem and his perception of what is normal/acceptable at work. DP confessed to feeling like if he leaves it will 'all have been for nothing', and this seems to be his biggest reason for staying, combined with the fact he said he can't shake this gut feeling that the company is about to take off and therefore him with it, and he doesn't want to miss out on that. Yet, he recognises this situation can't work long-term unless things change, and so he's going to walk away if he can't come to a better financial/working hours/work from home deal with work in his performance meeting in the new year. We will see, but this is a breakthrough.

I definitely think that for me, the money is huge factor. The wage when considering his commute + anxiety just isn't acceptable. He mentioned moving to a role closer to home to cut commuting costs if it comes to it, he also floated freelance as an idea if things go wrong when he asks for more money/flexibility in his meeting. Fingers crossed.

Well done OP. Sounds hopeful. Fingers crossed.

It sounds as if the company is deliberately giving him mixed messages - he is doing good work and getting good feedback for his work, but the boss is deliberately playing him down, saying he isnt ready for a reference, that he doesnt deserve more money, etc. It is his statement that it would all be for nothing if he left speaks volumes, because how on earth would 4 years experience and a portfolio of work be nothing? He needs to look at his time in that company as his time served at Junior level - he now is ready to move up a step, and his current employers arent offering that.
They know damn well that he is an asset, which is why they dont want him to leave. They probably know that he is worth alot more now, but dont want to pay him.

To be honest, asking the boss about a reference for a potential new job that he hasn't even applied for shows some naivety.