Are threeway relationships successful?

Depends on how open minded the people involved are.

Depends on how they make it work.

If its just about sex, as long as there is mutual hot sexual attraction going on, oh yes.
If there is actual friendship or even love involve, as long as each party accepts all the dynamics involve then yes again. I could imagine this relationship as having its advantages if done right or turning into something horrible if fumbled.

I agree with @Hibernate. It depends on the depth of the relationship between each of them as well.

I don’t know, just a minute i’ll ask the wives…...

thank you all for your answers. i am dating a couple rite now as a single female. it is tricky cuz i am finding myself more attracted to the man than the woman. imagine that. i can sense her jealousy and insecurity. i need to be more sensitive to the woman. the man is jus getting a thrill i think. thanks again for all ur contributions.

Three people can certainly have a successful relationship if they are all on the same page about the relationship. If the problems like jealousy, dealing with social controversy, and many others are things that the three people are willing to face, then sure. Just remember that communication is key to any relationship, regardless of gender, age, or number of people in it.