When it comes to love, debt can be a dealbreaker.These days, one-third of millennials would consider breaking up with their significant other because of a financial secret, such as hidden debt or a bad credit score, according to TD Bank’s fifth annual Love and Money Survey released Tuesday.Still, more than 1 in 4 millennials currently keep a financial secret from their partner, TD Bank also found. TD Bank polled more than 1,700 adults in July.These days, significant debt is harder to avoid, particularly among those just starting out. A typical millennial carries a hefty burden — about $23,064, according to a LendingTree study — mostly due to record-breaking student loan balances, sky-high rents and car loans.To take control of financial troubles, “step one is understanding what is coming in and what is going out and make changes for the better,” said Jason Thacker, the head of consumer deposits and payments at TD Bank. “Taking stock in what’s real and balancing that over time, whether it’s personal, professional or financial.”In 2 out of every 5 couples, one spouse admits to lying to his or her partner about money, according to a separate survey by the National Endowment for Financial Education. In addition, 75% of those surveyed said financial deception has adversely affected their relationships.More from Personal Finance:Is debt a dealbreaker? Couples say it depends on the typeFor young couples, money woes take a heavy toll 1 in 8 couples blame student loan debt for their divorceThe leading cause of stress in a relationship is finances, according to a study by SunTrust Bank. The research found that 35% of people named money as the primary trouble spot with their partner.In fact, 59% of divorcees said finances played a role in the breakup of their marriage, and 20% said financial conflict was a significant factor in their divorce, according to a separate survey by Experian.On the upside, more than half, or 55%, of millennials plan to disclose their secret within the next year, TD Bank found.And that may be the key to living happily ever after.The majority of Americans — both men and women — now say they prefer a partner who provides financial security more than “head over heels” love, according to a Merrill Edge report.Subscribe to CNBC on YouTube.