I have had a 24/7 sub and what happened was i came to think of her as a constant strain on my imagination and life in general, simply because i felt i had to judge myself for every command and decision, instead of just going with it and maybe finding out not to do so again in debriefing.
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If your not ready to take on the task either for lack of desire or insecurity. Then dont ruin a good relationship by changing it. Maybe thatll lead to other issues but thats life for you.