Yes, you can avoid all her sex scenes, but do you really want to deny her a fulfilling sex life?
I know most games have a harem ending, but honestly at this point I can't guarantee that this will happen.
I try to plan as far ahead as possible, but if it seems logical to me to end one of two relationships in order to continue the story, there will be such a decision.
I am sorry if this displeases you, however, there is always the possibility of playing multiple routes.