What many people seem to overlook is the well documented fact that DIFFERENT PEOPLE have different LIBIDO LEVELS (sexual desire levels).
People are often classified as LL (low libido) and HL (high libido) people.
Now low libido can be caused by EITHER: a. physical issues/problems or b. emotional/psychological issues. It can also be caused by not be turned on (or being turned off) by a partner, how the partner makes love or the ambiance and surroundings where it takes place. This kind of low libido is variable and can be corrected by examining the UNDERLYING CAUSATION for a NON PERMANENT low libido.
However, some people who have low libido just do not care that much for or about sex and that might be their permanent state. In other words, for some people that is their "norm" (their normal state).
Just as for some they might be High Libido as a permanent and natural state.
When 2 LLs marry or 2 HLs marry ... they will be "sexually compatible" with similar wants/desires/needs in terms of sex.
But when a LL and a HL marry ... there will be a difference in sexual desires and needs and this can cause a huge problem. Once reason the problem can be so huge is most don't understand it can be the "norm" for the other person; most take it personally that they are being rejected or neglected (HL)or used or harassed (LL). When those feelings exist (FROM WHATEVER CAUSE, sex or otherwise) they tend to fester and grow and they will create RESENTMENT or HURT FEELINGS and that can be the beginning of the end of the love or the marriage/relationship.
BEST SOLUTION in a HL and LL situation is SEEK HELP. See a sex therapist and/or start with a medical doctor to eliminate physical reasons and fix any physical problems ... and if all checks out fine physically, then see a sex therapist to explore the other non-physical aspects of a LL and a HL trying to compromise and make each other happy.
Good luck.
ROB