Can I get off at my layover instead of destination

Can I get off at my layover instead of destination?
My boyfriend lives half way between detroit and buffalo and it's 150 dollars cheaper to fly from Madison, WI to Buffalo then Madison to Detroit. My question is, if I book a flight from Madison To Buffalo with my layover in detroit (which is 3 hrs and47 minutes) is it possible to just get off at detroit? Someone I know said they'd cancel my return flight if I did this because I failed to show up to my flight in detroit, but if I already checked in, how would they know?
Other - Destinations - 3 Answers
Random Answers, Critics, Comments, Opinions :
1 :
sounds possible just do not have any luggage in the cargo hold. I assume there will be other passengers getting off at then as well so who is to know. I guess the return flight would have some issues but then easy way - just call the airline and let them know - you have a ticket anyways.
2 :
Ive done this before, its very possible. The only thing you need to do is call the airline to make sure if you have luggage checked in cargo that it doesnt go to Buffalo- its easiest if you dont have checked luggage at all. Also- you do run the risk on the return trip of them giving away your seat in Buffalo for the entire trip if its a full flight since they dont know your not using that part of the ticket- so just call them to make sure your still set and they will make sure your second part of the ticket isnt given away.
3 :
No. You could do so on your return, if you had no checked luggage. It is true that if you don't complete your out-bound trip, they will cancel the return trip. How would they know? When you don't board for the second leg of your trip, they'd know you're not flying.