There are some instances of bad conduct that are unethical but that are not illegal. One can ask whether something is ethical, whether it's legal, and (a third separate question) whether it should be legal. Each of these is a legitimate question. The questions won't necessarily all have the same answer.

You write, "You are arguing for a society, a culture, where it isn't men's fault if they pressure others to have sex with them." No, I am not, and I would appreciate it if you would refrain from putting words in my mouth.

I said that the man in Example 1 was selfish and insensitive. That's criticizing him, not excusing him. "Immature" can be an excuse if said of someone who's not of legal age; said of an adult, however, it also is a criticism. To state what I thought was clear in my post: I do consider his behavior unethical and I do think it's his fault. As I understand the current law, however, he has not acted illegally, and I would oppose making such actions illegal.

You're right that I'm considering a continuum of gray-scale cases. In the real world, that's what actually comes up. In the context of deciding what should be illegal, it's very important that laws, especially criminal laws, give people reasonable notice of what is prohibited, so that continuum has to be considered. Note that, just in this thread, there's disagreement about the ethics of the man in Example 3. That naturally raises the questions whether his conduct is or should be illegal.

Your food stamp analogy would apply to someone who pointed to examples of improper prosecution for rape and argued on that basis that laws against rape should be abolished. My own belief is that rape laws and food stamp eligibility criteria are both administered by fallible human beings. The inevitable result is that mistakes will be made in both directions -- some people convicted of rape are innocent, some who are guilty are acquitted or never even charged, some people get food stamps who aren't really eligible and some who are eligible are denied. Although it's true that we could completely eliminate the mistakes by eliminating the underlying law, that would be too drastic a solution. For both rape and food stamps, we should instead do our best to achieve correct results in each case, bringing the system as close to perfection as possible while acknowledging that we'll never succeed completely.

Logically I would end this post there. The problem is that I said "some people convicted of rape are innocent," which, in the unfortunate current atmosphere on DU, might well prompt the charge that I'm a "rape culture apologist" because I'm "emphasizing" false prosecutions or parroting an MRA talking point or whatever. To try to avert that distraction: I'm sure that the number of guilty people who are not convicted greatly exceeds the number of innocent people who are convicted. I was merely listing the problems, not quantifying them.