The price of unfaithfulness is so high that it is unreasonable. Therefore one is wise to avoid tempting himself or herself by continuing to admire the "merchandise."Most marital infidelity occurs because the parties involved continue to spend time together. Here Solomon advised avoiding the company of a temptress (cf. 2 Tim. 2:22; Matt. 5:28-29).
The price of unfaithfulness is not just physical disease (v. 11b), though that may be part of it, but total personal ruin. Infidelity dissipates all of one's powers (v. 9a). Others will exploit him (vv. 9b-10), he will hate himself (vv. 11-13), and he will quite possibly suffer ruin in his community (v. 14). Verse 9b would fit a situation involving blackmail, a not uncommon accompaniment to marital unfaithfulness.
"The use of both flesh' and body' [v. 11] underscores the fact that the whole body is exhausted."70