LizzieC: "The two women concerned, who seem to have had 'one night stands' with him, are saying he refused to use contraception when they asked. But it seems they still went ahead."

Not quite. Ms A appears to be accusing Assange of splitting a condom during fully (from beginning to end) consensual sex.

Assange wore a condom, per her request, but she suspects him of splitting it during coitus and not informing her.

At no point was the sex between then non-consensual.

The allegation consists of the possibility that the condom may have split during fully consensual coitus, and he failed to communicate the fact that the condom had split.

As George Galloway said, poor sexual conduct, but not rape.
Rape is non-consensual sex, not consensual sex "so long as you're not married" so long as you've "had the snip" so long as "you're a millionaire" etc.

In the case of Miss A, if true, then Assanges wrong, was deceitful behaviour during consensual sex, not rape.

Considering how tough it is to get a proper conviction for 'non-consensual sex', I don't like to see the term "rape" made a complete nonsense of for deeply dubious political purposes.