If you don't want to pay for the new content that's fine. But I need to charge for the time I'm spending on this because I can't work for free. I spend a lot of time making these games. I don't think it's very expensive for the amount of content you get.
When they pay you recived for lewd mod 1 wasnt enough the normal thing to do is raise the price, not break the game up into pieces. Especially since lewd mod 1 promised all future updates to buyers. At best its false advertisement and at worst bait and switch.
I run a small construction company and if i take on a job too cheap (have happened once) i have to eat the loss, i cant lock up 2 rooms and demand payment to give them access.
And while i agree $5 is a good price for the current content thats what should have been charged for lewd mod 1, maybe even $10 so you can continue the work.
To be fair, when you build a house, there is a defined end-state and you're getting paid by one individual. You can negotiate an agreed amount and you are guaranteed (at least contractually) that you will receive that amount. This situation is quite a bit different, his work is ongoing with no defined end-state, and whether or not he makes enough to cover his costs is down to whether or not enough people buy.
If double the number of people had purchased LewdMod1, it may not have been necessary to split it.
That "Eat the loss" is a lot easier to justify when you're talking about a project that can take a year at most, not when this may be a commitment that you keep for years into the future.