Perspectives vary but in general and given what most cultures teach their children, marriage is a right of passage, to be with someone you came to love and make that person your own, to procreate and continue the human tradition of having families and to settle down after coming into adulthood. Also, good sex can be learned so there is no need to confuse children with sex issues when they are young. If the feeling is mutual, and two adults come to love each other and they marry, naturally their intimacy would feel good to both. If the man is lacking in experience, his lady should point that out and get him to learn to satisfy her. That is because she loves the guy and married him for a reason. Islam also encourages good sex and a woman is granted the right to divorce if her husband is not meeting her sex expectations. Islam is actually liberal about sex and no shame is attached to it if people are engaging the sex legally under faith. Allah says in the Quran "come to your wives as you please". Humans are supposed to enjoy intimacy. That is why women have 8000 nerve endings on their clitoris which is double the amount on a man's Penis.
Just to say few words about why people marry. Everyone has their own reasons. .