The time will come, infact maybe several times, whether you planned for it or not, when you will be home alone. For clarity, I am refering to husbands and wives, not live-in partners, nor housemates, nor anything other than legally married couples.
A few spouses may see this as a time to indulge in stuff (fill in yours) you won't be able to fully disclose to your spouse when he/she is back. Although that is an extreme, most people would just go through such periods not knowing exactly how they spent the time.
I have been through a couple of home alone times in my 3year old marriage and of all my activities during such periods, i can tell the most fulfilling- a retreat.
A retreat is something that rejuvenates you, its a time of introspection, revaluation and putting your life in order in all ramifications. You come out of a retreat re-energized and your life and marriage will be better for it.
I invite you to write in the comment section, from your personal experiences, what you enjoyed doing the most during your home alone time(s).