Long-term relationships sometimes can stall out, for lack of emotional warmth. It's not that the partners DIS-like each other, they just feel lukewarm towards their mate. Or, so says Dr. Finkel, author of the "All or Nothing Marriage".
Many people are looking to their partners to replace the companionship and emotional support once provided by extended families and local institutions like churches, bowling leagues, bridge groups, fraternal lodges and garden clubs. Meanwhile, though, many couples are so busy with their jobs and parenting that they’re actually spending less time together by themselves.The post at the link above has some suggestions about how to turn up the fires - the ideas are called "Love Hacks". They seem to be based on some degree of evidence (although recent investigation of many social science research suggests that throwing darts at a target would produce similar results). They couldn't hurt, however, and might be useful.