Wanted to know if couples who abstain from sex prior to marriage tend to have more successful marriages?

Not necessarily : I have had arguments for both sides of this question. If sex is a dealbreaker have sex before marriage with precautions, and decide if you want each other. If sex doesnt matter and values does, discuss that thoroughly before deciding to settle down.

Jury is out: There have been studies to suggest that this might be true, but so far those studies have been of questionable quality. In short, the jury is still out on this.