> a rape should involve physical coercion or heavy psychological abuse
This isn't the test in pretty much any European country at the very least. All that is required is generally the absence of consent for the specific act. If she has said "no" or had diminished capacity to object or consent (e.g. been drunk or asleep), then you generally don't have consent.
In this case part of the allegation is in one instance that the woman was "half asleep" (potentially unable to provide consent, though in this case the defence will want to question exactly what is meant by "half asleep" in the statement), and secondly that consent had previously given for intercourse with a condom and that it been made very clear to Assange there was no consent to sex without a condom, but that Assange allegedly intentionally sabotaged a condom (if he did, then that would be a crime in a whole range of countries).
If those allegations are true as they have been presented, then it would be some form of sexual offence pretty much everywhere, whether rape or sexual assault.
Of course we don't know if they are true, or even if they accurately represents what the women told police.
> You can't decide a sexual intercourse was actually rape some days after the fact;
No, but you can decide you need to report it days after the fact. While a delay in reporting a rape is often used as an argument by the defence in rape cases, it is fairly common for rape victims to take their times to come forward.
More importantly in this case the alleged victims allegedly did not report a rape but went to police to ask if they could compel an STI test, and the police started a rape investigation on the basis that the details as described by the women allegedly meets the standard of sexual offences under Swedish law.
> The rapist and the victim generally don't part in good terms as apparently happened in this case.
Victims often continue to live with rapists for years. Or date them. Or work with them. To those around them it can often perfectly well look like they're on good terms. This is part of the reason why rapes are so hard to prosecute, because so often it devolves to a "he said, she said" where the way the victim have acted is hard to understand for juries.
Assange may very well be not guilty, but I don't think any of this remotely rules out that he might be guilty.