I think since each persons relationship is different in ideals your going to get a different answer. Look up the post titled Your ideal relationship to see each persons views.
Mine is.. eventually all living together in a V situation. Now I have hubs(s) and a guy Im dating now but dunno how things will work later on down the road. When that ideal relationship happens.. well it will be together and separate. The ultimate part is together. The life shared. Some of the sex. Theres part that is separate.. I want the connection with both. Which means more one on one time. with each. Sexual and otherwise. I think theres a balance. When both your partners are involved with one another it is more a group connection as well as a separate connection with each of you..
If your partner was a partner with someone outside that you never see or know then yes thats sep. From the looks of yours its a together and a separate. So technically.. the right answer is both of you are right