Lying, no doubt about it.

Angela, 16
Bella Vista, AR  USA

lying, sleeping around, deception, stealing...

Frodo
age unknown, parts unknown

Dishonesty, without a doubt.

Dianne, 16
Ontario  CANADA

Lack of communication.

Jane, 60
West Linn, OR   USA

mistrust

Firelady, 23
Dallas, TX   USA

Dishonety. Relationships can survive a lot if the partners are honest with each other.

Deb

Personal differences.

Alias Irrelevante

One partner being obsessed with changing the other is, in my opinion, the most dangerous thing. Someone should never pick their partner with the idea that "I will change him/her." That rarely works. Of course, too, it is also dangerous when one partner is far more taken and obsessed with the other than the other is with them. That is deadly to the heart as well.

Johanna, 18
OK  USA

Betrayal.

Jennifer, 19
Wilkes-Barre, PA  USA

The most dangerous thing to a relationship is attitude. If you have a bad attitude then relationships just don't work out.

Marci, 56
Diamond, OH   USA

Lack of trust. Without trust jeslousy comes in, insecurity comes in... it makes a big big mess.

Maggie, 20
Sandwich, IL   USA

If you start losing your own sense of self because of it; that's not healthy. I think that happens with a lot of young people.

Fisch, 45
Preston, CT   USA

Dishonesty.

Talia, 23
Wilton, CT   USA

betrayal

Jaden, 21
Brampton, Ontario  CANADA

A reason to lose trust in the other person.

Laura, 36
Lowell, MA  USA

Selfishness.

Jill, 60
Saylorsburg, PA  USA

Lack of honest communication.

Felicia, 35
Lowell, MA   USA

I think any form of cheating would totally destroy any relationship (Most times)

Blaid

that one is easy - DISHONESTY !!!

Brad, 20
Sydney   AUSTRALIA

Lack of communication.

Ry, 23

I think the most dangerous thing to a personal relationship is dishonesty. If you are not honest with one another than you have nothing.

Heather, 15
TX  USA

The most dangerous thing to a personal relationship would be lack of trust.

Anjel, 20

Depends what kind of relationship, doesn't it?

Karen, 21
Marshelltown/Ames, IA  USA

A third person.

Janet, 42
E. Brunswick, NJ  USA

Fear.

Eric, 19
Beverly Hills, CA  USA

Yesterday / Tomorrow