Sexual consent is granted in stages, and acknowledged by the lack of phsyical resistance. Consent to progress can be denied at any stage, and can be withdrawn from the current stage. However, its important to understand that when progressing sexually, consent is always acknowledgement that one is allowed to proceed to the next stage.

This may seem backwards, but involving speech during sexual activities is mixing oil and water. Sex is used to satisfy emotions, and speech is used to satisfy logic. Neither party participates sexually because its logical, but rather to satisfy emotional needs. Sex is an emotional transaction, and logic (provided by speech) has no place in emotions. And sex would be rare in the absence of emotion.

The emotions either party wants satisfied may vary. The most common emotional needs satisfied by sex are:
1. self-worth: for either sex, knowing their value to a community (sexual value being any human's most important value)
2. safety/security usually for females, given to them by males, the males interested in protecting their offspring

Sex is an emotional transaction, and it's wrong sebsequently alter the transaction's terms.
Examples of altering the transaction's terms are:
-expecting a shorter/longer relationship than was agreed
-bearing/not bearing children than was agreed

Transactions are examples of consent. And it's wrong to allow either party to ignore their responsibilities in a contract. However it's not only allowed, but encouraged. Both sexual and marriage transactions are having their terms altered. This is theft; it's trading equal good for equal good, then extorting the other to provide more than stated by the transaction's terms.

"The market is not an invention of capitalism. It has existed for centuries. It is an invention of civilization." -former USSR President Mikhail Gorbachev

The preceding quote is that of Gorbachev, who guided the USSR through its dissolution. In the USSR, contracts were not respected, and people did not deal with each other honestly, according to the terms of contracts. They acted pragmatically, for the moment. In the USA, contracts were respected, and people dealt with each other honestly, to achieve mutual benefit. Contracts were consented to, and respected.

And now Russia is increasingly respecting contracts while the USA is increasingly ignoring them.

When we continually ignore contacts, how do we expect anyone to follow them? If there are no penalties, (or worse, the courts ignore them), do we expect the continuation of civilization?
And if civilization is no more, who will suffer? In a world where physical strength and pathological ruthlessness is favored, what is our quality of life? How will we be different from animals?

tl;dr: Consent is agreement to a transaction. One cannot change the terms of a contract after benefit has been provided. This is truly non-consentual.