Look, it happens. Sometimes you end up sitting next to someone who's not only age-appropriate and single, but attractive. The situation being what it is, the captivity of the plane can either be the best or worst place to make your move.
I was in Bangladesh about to climb on board the last airframe of the type operated by Biman Bangladesh Airlines, the last airline using the DC-10 in scheduled passenger service. For the final commercial flight we were booked for thirteen hours en route to Birmingham, UK.
Would you board an airplane knowing you had the flu? Would you worry about possibly infecting other passengers or airline crew? The decision whether or not to fly when you're sick is complicated because it's influenced by a number of factors.