Operation Proposal (2012)

I recommend this both drama because , Male lead and Female lead
try to solve problem
In one drama explosion and another student murder/suicide

Both are time-travel drama because of their first love and the guy is trying to change his destiny and make the girl love and marry to him.

They're both about marriage, time travel and regretting your past, when I started watching "Go Back Couple" I immediately thought about "Operation Proposal" :)

Operation Proposal è il remake coreano del drama giapponese Proposal Daisakusen. Nonostante la storia di base sia la stessa, i due drama differiscono in molti punti.