There's loads of fairly serious red flags here.
The 'I don't know why you are with me' is emotional manipulation. It's designed to get you to fawn all over him, tell him why he is amazing and reassure him that when you live together your money will be shared
I bet there's also 'you are too good for me' thrown in for good measure. When a man has said that to me my response is 'if you believed that and you genuinely cared about me, you would walk away. If you really believe you are dragging me down, but care about me you would walk away rather than damage me'. Then the relationship is usually done. Because either they have shown they are trying to manipulate me OR that they don't really care for my well being just their own.
You can't compare career success, unless you work for the same employer and met doing the same job. My best friend is a student, she returned to uni. In that time I have had huge promotions. She isn't jealous. She wants to be a midwife, my job has no baring on hers. She needs to take a particular route that I don't. I don't need to go to uni. She is working towards her own success, that's her focus.
To me, when people feel envious, it's because they don't think the other person doesn't deserves what they have. It's 'why not me' thinking. As though the other person was just handed several promotions and it's completely down to luck, but they just haven't had the same luck. People who are envious, get wrapped up in that, rather than looking at how they can improve their own position.
Its not your job to make yourself smaller or make him feel bigger, because he he doesn't know how to handle this.
And why on earth are you offering to pay for a house for you? Would you really buy a house, you put all the money up and put it in joint names? Why? To make him feel like he has something? He will have it because you bought it. That won't help. And if he leaves you, you could find you and your child having to move to give him his money.
And if its not joint names, he will be constantly digging that, it's actually just your house. And this will get worse.
And your home would be at risk if the relationship broke down?
This relationship is heading 2 ways. You end up, spending your life trying to make him feel better about your success, while he plays the sad little boy....but also while benefitting from your success.
Or he will benefit from your success and then end up resenting the fact taht everything he has is mainly down to you.
If he is too insecure, to be in a relationship with a woman who earn more, he shouldn't be in it. You dshouldnt be in a relationship with a man, that makes your successes all about how bad it makes them feel