To call it 'gross and unattractive' is a huge understatement and very naive.
I work with rape victims, and not only is it immoral in that it's a violent assault on an innocent part for absolutely no valid reason, but it's evil and unforgivable.
Of course it hurts! If a woman doesn't want it to happen, in most circumstances her muscles contract, which makes it extremely difficult for a man to enter her without real violence. I've heard girls and women explain how it hurt so much they wanted to die - and really thought that they were going to.
And unless sex is consensual, the unwilling party does NOT enjoy it at all.
Many women DO find sex painful, unless the man takes a long time on foreplay. Rapists don't do that because they're only committing a violent assault because they enjoy hurting and terrorising a female. Sex is meant to be an act of love between two consenting adults.
You ask how does rape harm the person being raped? It makes them feel severe pain, dirty, terrified, violated, ashamed, and most victims have psychological problems for the rest of their lives. They never feel safe again, won't go out alone, can't have normal relationships - the effects are terrible and very often permanent.
I really hope you can understand this.