My knowledge of this is that “within the overall act of marital relations” means that the Chruch teaches that foreplay is acceptable (mutual masturbation, oral sex, etc) so long as the final act of all this ends with the male’s climax inside his wife during sexual intercourse. I heard Fr. Stan once say that you can “swing from the ceiling fan if you want so long as you end with sexual intercourse.” After the male’s climax, from what I have heard, it is still permissible for the woman to be stimulated and climax, so long as it is still within that same marital act.
As far as what Logan presented, I would have to say that I believe it was Van Halen that said it the best “C’mon baby finish what ya started!” Anyhow, I know that like you we have many distractions and the times that we have for out “alone time” can become less and less. By the time we have the time, we are both so tired. In your case, I think that a lot my lie with the intent of the acts that you are performing. If you know that you are not going to be able to complete the act, then I think that this may be bordering on sinful. Now I am rethinking that statement. I guess that brings up the question of what if you and your wife (for example) have a night planned out, a nice dinner, and you are planning to make love that night, when you talk on the phone, you tease each other about what will happen that night. Would that be sinful? Or foreplay?
I guess a lot of it would depend upon the intent of the act. For example if you and your wife started foreplay with the intent to end in intercourse, but were interupted by the kids, I would say that is not sinful. Would teasing be sinful? That is tough to say as that seems to be the root of your question. I am interested to see what others have to say.