He is in love with Jane. Otherwise he wouldn't be spending so much money on her. But if he is in love with Jane, Mary is going to leave him. So it looks like Mary is going to leave him. It is one thing to let people harm themselves, but smokers don't just harm themselves.
Secondhand smoke can cause health problems for nonsmokers.
Some nonsmokers suffer from headaches, runny noses, and itchy eyes as a result of exposure to secondhand smoke. And secondhand smoke can cause lung cancer even in nonsmokers who are regularly exposed to smoke. We have good reason to ban smoking in public places. The Challenger shuttle explosion could not have been cause by a leaky valve. If the valve had leaked, the instrument panel would have registered it.