Personal space is a basic human need. If you never have time apart from your significant other, there's less opportunity to recharge and reflect on the relationship. When couples spend increasing amounts of time together, it's important to be able to request time apart. Otherwise you'll feel a need to escape and risk hurting your partner's feelings.
Map Out Your Lives
Time is a precious commodity. Grab a day planner and compare personal schedules with your partner. Pay attention to whether couples time gets in the way of exercising or doing solitary activities like journaling. While noting any deficiencies in "alone time," also take stock of important dates to spend together. Make space for shared vacations, holidays and weekend getaways. Doing this together will show that you are taking the relationship seriously while protecting your own interests.
Next, sketch out your living space with your partner. Note whether there is shared space, along with clearly marked personal space. The science of proxemics, which studies the dynamics of space on interpersonal relationships, shows that everyone needs a minimum amount of physical distance to feel comfortable. Create separate areas that take into account both of your styles, interests and tastes. Identify times during the day (for example, after work) when you can retreat to separate spaces to decompress.
Politeness and word choice go a long way. Saying something simple like, "I love you, but I need some time alone," works a lot better than simply disappearing for a weekend. Along the same lines, if your partner has a particular need to spend time with you, suppressing your needs for space may be warranted in order to show him/her that you care. In the end, it's best if you negotiate your mutual needs for space, while emphasizing the benefits of space for a long-lasting, healthy relationship.