I regularly remind students during lessons NOT to worry if they found no time for practice, which seems to happen at least one week a month. Children usually have the luxury of a daily, weekly, monthly routine. Those were the days!
Adults not only have serious responsibilities, they also carry the guilt thing along. Of course, some do a better job of keeping it at bay, but it seems to play a role in all our adult lives. I would like to say "for better or for worse," but I think it's rarely "for better."
Most of the time the guilt it self-imposed penance, it seems. We often feel we are neglecting loved ones or neglecting our homes or selfishly spending money on ourselves. We don't question joining gyms or taking long walks or volunteering our time. Why do we believe adults don't need to express themselves artistically, even though we know this is essential in a child's life?
Adult students who seem to most enjoy their lessons -- and who make the most progress -- have a less-guilty-aura about them. Even though their circumstances are similar to other students, they tend to brush things off better and have a more secure sense of their role in making music an integral part of their lives. When they have periods of diminished practice, they don't fret so much, knowing the piano will still be there when things ease up. This positive take on things makes all the difference.