The title of this post is even a bit misleading, as friendships are infact relationships themselves, so I wanted to emphasize the importance of that point. I think this is generally more of an issue for young people, as older folks are only friends with other people who are also married and have obligations to their family – but if you`re not an old married couple and you`re acting like one, you need a wake up call.
There`s several reasons why partners in couples need to maintain healthy social relationships outside of their relationship. One obvious one is that you shouldn`t lose your friends unless they really aren`t right for you. While you may be in an infatuation stage now where nothing else seems to matter, it will matter later on when your absence of real friends actually hits you (hint: your partner isn`t always the type of friend that you need at certain times, especially if it`s a time where you need help regarding your relationship).
The other reasons have to do with codependence issues. Couples who start to bail on their friends and spend all waking hours with each other are normally in for an abrupt wake up call in the future. This is not a healthy way to maintain a relationship. Couples need to spend enough time away from each other to ensure that each partner occasionally has the independence and autonomy that every person needs as a human being. Also, it is true that people can start to lose their social skills after isolating themselves and stopping socializing. It sounds a bit extreme and ridiculous but you could probably think of at least one person you know, if not yourself, who has been in a situation such as this one. People fall into these situations easily, and it`s hard to shake off once it starts.
If you`re in a relationship make sure you give yourself enough time to spend with friends and even family without your partner. You should also be able as a couple to go out and socialize with each other`s friends and family – as any inability to do that would probably lead to quite great friction later on.