I don't think it makes a lot of sense or is particularly helpful to compare rapists of adults with paedophiles. In most incidents of adult rape – often including the rape of present or former partners – it is less a sexual crime than a crime of violence. It is very often to do with power and control. While some paedophiles violently rape children, many more spend much time and care grooming their victims, convinced that they are creating a loving, consensual mutual relationship, presumably because they are unable, for whatever reason, to create such a relationship with an adult. Surely it is at least partly because they have convinced themselves that the "relationship" is of this sort that they cannot recognise the awfulness of what they have done. The rapist of adults, on the other hand, tends to justify their actions by denigrating the victim who "deserved" what they got, even when he or she is a stranger.