Blackmailed into a relationship?

Like the other party knows the other's secret/weakness or something. And no debt or money should be involved; I've seen way too many of those dramas.

Thanks =)

 emeraldarrows:

 Not a secret or weakness but not for money...Well-Intended Love?  The FL learns she needs a bone marrow transplant and the ML helps her only if she marries him in exchange.

Except of course she DIDN'T need a transplant at all and the ML lied and set the whole thing up, bribing staff and faking medical records specifically to coerce her into doing what he wanted. MUCH worse than merely blackmailing her.??