Maybe I Just Don't Understand How Relationships Work

Really.  Maybe I have no clue as to what makes a healthy relationship.  I've been with Ken for nearly twenty years and I think we've got a great one, but from comments and remarks I hear from others, we're just doing it wrong.

Apparently, to have a healthy relationship, you must be joined at the hip with your partner 24/7.  Independent thought is unwelcome and independent activities is the worst crime you can commit.

Okay, maybe I'm exaggerating, but I just don't understand why a huge majority of my couples friends are not allowed to do anything without their other half.  If an opportunity comes up for one of them, it's often passed over because it's either only for one of them or one of them is unable to do it, so it's off the table.  I don't know how people can live like that.  I love Ken dearly, but if I had to spend every waking hour with him, I'd kill him.  I like to do things on my own as much as I like doing things with him.  If he's got a chance to do something but I'm not free to do it, I'd feel like dog shit if he had to miss out on it.  Case in point.. Next weekend he's taking off for a solo vacation.  He found a killer fare for a cruise out of Florida and he's going.  By himself.  He's asked me a few times if I wanted to go, and while I'd love to drop everything and take off for a week, I've got a lot of time already scheduled off at work over the next two months.  Adding another week was just not feasible.  Because I can't go, am I going to hold him back?  Hell no.  I'll miss him, but at the same time, I'm going to enjoy a little downtime just for me.  It's a win/win situation almost.

Anyway, many of my friends cannot wrap their heads around this concept.  I don't know why.  I don't know if it's a trust issue in their relationships or a control issue or what.  I'm not a therapist, so I can't answer that.  But seriously, is your relationship on such shaky ground that you can't do something on your own?

Four or five years ago I took a vacation away from Ken.  I flew to Texas to spend about a week and a half with my friend Freddy and his family.  Everyone Ken knows questioned him about this.  Seriously.  Why would I take off for such a long time without him?  One "friend" even went so far as to sit Ken down to let him know that the reason I went to Texas without him was to fuck around.  (Keep in mind this person's longest running relationship lasted about three weeks.)  Seriously.  What the fuck is wrong with people?  So even people not in a relationship think doing something without the other is wrong.

One of Ken's friends is an exception to the rule.  He thinks it's the greatest idea in the world.  He would love to do it.  But he's married and he can't even think about going to the grocery store alone without his wife flipping out.

Can someone explain to me why doing things apart, whether it's going to the store, visiting a friend or going on a vacation, is a cardinal sin?  I really don't get it.