Sexual relationship

depends purely on the circumstances. 
but at the outset, it may be said that it is not rape when there is consent. 
court will want to know how the consent was obtained. this will decide the fate of the person. 

Two things

1) If it is an academic question then you can read lot judgments some taking this stand some opp stand at the same time most imp. factor taken by Hon. court is circumstances under which this relationship took place , this is most imp. deciding factor.

2) If you are  boy and involved better keep your word and marry , don't breach the trust same thing can happen with girl in your family.  And most imp. legally when such proceedings are going on in Hon. Court  even if you are not convicted still you are denied career opportunity including Govt service etc. (Such matters we have come across selected in exam 2 or 3 rank like banking due to pendency of case nationalized bank showed some judgment and rejected  the candidate showing that case is pending ) . Same stand some big corporates or good companies take we don't want such problematic people in our organization better avoid them.  So your career can jeopardize a lot this is observed. Additionally future marriage alliance with such boys  too have  lot problem . 

To avoid derailing everything better reguralize things and bring in track by marrying . 

Those judgments will not help a person who has deliberately made such a false representation. 
However, it is possible that in starting the intention was genuinely and bona fidely to marry, but later, owing to circumstances or due reasons, such intention couldn't transform materially. 

Sextual intercourse under false marriage promise is rape.