Yes, Assange got sued for consensual sex with two women, without using condoms and I dont know why it is illegal in Sweden, but it is clearly an excuse to lock Assange.
The problem is (as Emigre mentioned) deceiving the women over the use of condoms. You know, lying about something that could lead to pregnancy or STDs. That's pretty serious.
You can deceive a woman about that only if she is blind and has taken a pain killer