At the start of a new relationship, it's common to feel that butterflies-in-your-stomach, stars-in-your-eyes rush of emotions. But when exactly does the big "L" word come into play? When do things go from infatuation to really being in love?

Men take an average of 88 days (about three months) to tell their partner they love them, whereas women take an average of 134 days (four and a half months), according to a 2013 survey conducted by YouGov and eHarmony.

They also found 39% of men say "I love you" within a month of dating someone, compared to 23% of women.

That said, there's no definitive amount of time it takes to fall in love that applies to everyone.

Some people wait much longer to say, "I love you," whereas other people swear they've experienced love at first sight. "Like most things, it does depend on the person and the circumstances," licensed couples' therapist Lexx Brown -James, Ph.D., LMFT, tells mbg.

Case in point: An 2018 survey of 1,000 British men and women found that while more than half of them take over three months to say, "I love you," 32% of women and 29% of men say it in one to three months—and 10% of women and 14% of men say it in just one to four weeks.

One 2017 survey found 72% of men and 61% of women believe in love at first sight, and a 2004 study found about a third of Americans say they've personally experienced it.

There's some science that backs up the concept: Some research suggests people decide within seconds whether they're romantically interested in someone, and neurologically speaking, it takes only one-fifth of a second for the neurochemical reaction associated with feelings of love to fire off.

But other research discounts the theory. A 2017 study in the Personal Relationships journal orchestrated a bunch of first encounters between single strangers, and the researchers found feelings of instant attraction can indeed happen in a first encounter.

Some people described these feelings as "love at first sight"—however, these people didn't report feelings of intimacy, passion, and commitment as part of their experience. The main predictor of a "love at first sight" experience was finding the other person physically attractive.

Love can be thought of as all three elements combined, according to clinical psychologist Bobbi Wegner, Psy.D. (But even love itself goes through phases—here are the stages of a relationship to expect.)

"Falling in love is something people often say they can feel immediately, and others say it feels like a slow burn, a winning over," Brown-James says.

How long it takes to fall in love will vary depending on the individual and the relationship they're in.

There's no real way to fast-forward the process and make someone fall in love, but there are plenty of ways to nurture a relationship so that those feelings can more easily manifest.