From a responsible point of view, you must get married before studying for a PhD, but the specific situation also depends on your family, your values and your attitude towards income. If you want him to make more money, or because his current study has affected his income, then it makes sense that he wants to study for a doctorate first and then find a good job before marrying you. After all, being responsible for a person is not only about getting married, but also facing various life problems in the future. Buy a car, a house, send children to school, etc. It's not a small expense, so if you put pressure on him about money, then there's nothing wrong with what he does. We can be together when waiting for him, no matter what the final result is, it won't be too bad. But if he unilaterally wants to wait until he finishes his doctorate before getting married, then your situation is even more dangerous.
A friend around me has the same situation. His wife is studying PhD, and it's the first year, but their children are all 5 years old. Get a certificate after graduation, then get married and have children. Nothing is delayed. He is responsible for making money to support his family, and his wife is still studying. Moreover, their relationship is very stable, and they will not feel that whoever pays more will pay less.
There are too many such examples around me, and there are many that have nothing to do with studying for a doctorate. This can only be said as an excuse. It may be because he wants to study for a PhD, so he must concentrate on his studies and not be influenced by other things, but this is really just an excuse, because if he really loves you, then he will definitely choose to get married before studying for a PhD.
Because men can choose to get married later, but women had better get married as soon as possible, because I think girls' youth is still precious, and they are most afraid of wasting their youth by making a mistake, because this situation is probably because he has not considered for you, and he only considers himself. He may think that after he studies for a doctorate, he will have more choices and may meet better ones, and you may just be his spare tire, otherwise a person really loves a person.
So the specific situation depends on why you two don't get married. If it's because of the man, you'd better give up, because such a person is not worth waiting for, and what you get after waiting may be giving up, so even if you don't want to give up now, you should consider your future and put your future on someone who doesn't think about you, and there will definitely be no good result in the end.