Many people go through their chemotherapy with their usual sex lives unaffected.
On the other hand, some people may find their sex lives temporarily change in some way during their treatment. For example, there may be times when you just feel too tired, or perhaps not strong enough to maintain the level of physical activity you are used to during sex. If your treatment is making you feel sick, you may go off sex altogether for a while. Anxiety may also play a large part in putting you off sex. But stresses like these can easily push everything else, including sex, to the back of your mind.