Don't force people to care
When people genuinely care, they don't need any prodding -- they do things because it comes straight from the heart.
People make time for and invest energy in the things and people that matter to them.
For example, if you sense you have to cajole your boyfriend into committing to you -- even after being together for several years -- what does that say about his interest in taking things with you to the next level? It communicates that he just isn't that serious about your future together.
Or suppose that your friend of 10 years seems to serve up a different excuse every time you propose meeting up for coffee. When getting her to say yes is like pulling teeth, that's when it's clear who's really invested and who isn't.
We can drive ourselves crazy trying to figure out why a person would act this way, but it would only be an exercise in futility. A person can do a 180 on us -- even our partner or closest friend -- and leave us totally blindsided.
Once you've communicated your interest in getting the relationship back on track after things have cooled off between the two of you, it's their turn to act.
People show they care through their actions, not just their words. It's easy to tell someone you'll call them tomorrow, or that the two of you will hang out soon, and not be wholly committed to following through. You're essentially telling the person what they want to hear just to end the current conversation graciously.
Oftentimes, people may lose interest in others when they know they don't need anything from them at the moment. It's those kinds of people who are driven more by selfishness than anything else.
But when two people truly care about each other, merely spending time together is sufficient. They recognize that to keep the relationship strong, both individuals need to call, text, and show interest in one another. If only one person is making the effort, the relationship likely has no chance of survival.
Never feel as though you have to be the one to accommodate the other person all the time. They should demonstrate that you matter to them just as much as they matter to you.
And saying they don't have the time is, of course, an unacceptable excuse. People make time for those they feel are deserving of it. If you're not one of them, consider it a blessing. It affords you the opportunity to spend your time with those who will genuinely value it.