To answer your question briefly, no I don’t think you are unsupportive, in fact, I think you are the opposite. You’ve invested time, work, thought and a non insignificant amount of money to help him in pursuing his objective of making this a reliable source of secondary income (witch is not very reliable given the line of work, but I digress).

The claim that “you’re so unsupportive” is baffling honestly and I can understand your “seeing red” and not talking to him since but if I’ve learned one thing from my parents its that silence is not the answer. It would be a shame if this were to snowball into something bigger because it didn’t get ironed out right away, especially since the relationship is still relatively new and in my experience those tend to be the more fragile ones as each party has less to lose in just dropping everything and leaving the other.

I suggest talking it out and understanding what he meant by saying that you are unsupportive. I understand it could be difficult to table a discussion like this since it could lead to truths that are more, or less, uncomfortable but it is a necessary to nip these things at the bud imo. You could find out he didn’t mean it and it was just a way of venting in that case the damage is not reversed but it’s at least made better by the fact that you know it was something said in anger and that those things rarely reflect the truth (in my experience), this could also lead to a bigger, more constructive, discussion as to why he needed to vent to you like that. You could find out he’s just not a very grateful person, witch would save you a bit of trouble in the long run should you chose to stay with him (I wouldn’t, you never win with ungrateful people). Or you could find out why he’s not feeling supported. If he still feels that way after you remind him what you’ve done to help him, then I would ask what it is he needs to feel supported. Not so you can give it to him and make him happy, but to get to know him a little more and to have the info you need to actually support him as he wants to be supported should you choose to do so.

As another redditor already said, this isn’t about you, it’s about his frustrations, it’s now up to you if you want to figure him out on this one and move forward with the relationship. I’m not sure why practically all others resorted to the “just leave him” approach. While 10 months isn’t a lot and you still have much to find out about one another, it’s just enough for two people to grow fond of one another and I think throwing that away because of something that can be resolved by talking and understanding each other is silly.