A hypothetical situation. The girl is playfully resisting on the sofa during foreplay. She looks into the guy's eyes with lust. He knows she's ready. She playfully resists a little more. He enters. Meanwhile, the camera is rolling and it doesn't pick up the playfulness of the encounter. This scenario may feel like a stretch, but if it were to happen, we all understand the consequences.
Another situation. She fucks you because she's desperate to get pregnant. She breaks the condom. Or she quickly runs to the toilet with the juice in the dom rather than takes it to the bin. If those eggs happen to survive, your life may be screwed due to a few moments of lust.
When you're at the maid agency and your SO picks the ugliest (but most competent) maid, but you're looking at the hottest one, agree with her, as you may be thanking her later.