There are those in this world who cannot make a commitment and stick to it, so it is best to understand that the two are not mutually exclusive. In relationships, people believe only someone who truly loves them can make a commitment. This is untrue, and many relationships where there is no love have flourished over the centuries. They are between couples who believe their duty to each other, their family or society is more important, and love between them has no place in their lives.
Arranged marriages are one example of a couple living together with commitment that does not include love, and there are still societies where this is normal. They get married and build their lives together, but not all of them will develop any affection for each other. Couples in these relationships uphold their duties to each other and family, but love and affection are reserved for someone other than their spouse.
On the opposite side of relationships is a couple where they have no commitment, but they do have love. Marriage may be completely out of the question for them, but that does not diminish their feelings for each other. They might each be in a marriage already, divorce could be something they do not desire and they settle for sharing their feelings while living apart.
In the modern world, there are few people who find love without a commitment to be acceptable. They see it as a sham if the other person is unwilling to give up everything to be with them, and the relationship often falls apart when this happens. They would rather suffer the loss of their loved one, and many of them go on to find relationships that fulfill their expectations. While there might never be the same deep love as before, they are happier with a committed relationship.