As the song goes: "Summer lovin', had me a blast."

But for dads with daughters who are falling in love for the first time, it might be anything but a blast. Unless that KABOOM! is the sound of Dad's heart exploding in sadness.

Summer can take a harrowing turn when family vacations and young romance intersect. Suddenly daddy's little girl who a year ago wanted to play tennis with you has now completely forgotten you exist. No, she's too busy texting, curling her lashes and scouring the beach for Todd the surfer dude.

"In a certain way dads really do feel jilted, bereft even," says neuropsychiatrist Dr. Louann Brizendine. "They almost feel like they've been left at the altar. Often they think, 'what did I do wrong? How do I get her back?' They'd had this really special, close relationship between dad and daughter then all of a sudden she takes the off-ramp from that relationship."

I remember taking that off-ramp. His name was Mark and he was older (27 to my 18), mysterious and gorgeous. And while my hormone-fueled brain was acutely aware my dad was having a hard time coping -- his wide, frightened eyes might have given it away -- the Mark vortex had rendered me incapable of caring much (Sorry, Dad!).

Here's what dad has to say about the experience:

"When my daughter began a serious relationship with someone several years older, beyond my sphere of influence and probably not to my liking, I felt threatened and powerless. While I may have wanted to feel that she had become independent and in control of her life, I felt a genuine sense of loss and a nagging fear that I may have not done enough to prepare her for the journey. It was one of the more difficult transitions I had to negotiate."

Oh man. Again -- sorry, Dad.

Kirsty Ewens says her father had a "total meltdown" when she indicated she wanted to live with her boyfriend. So he came up with a solution. He built another house on his property for her and her beau to live in.

"My dad has always overreacted in any fear he would lose my companionship," Ewens said.

Ya think?

"He calls me 2-3 times a day," she says. "We live (300 feet) apart."

While Kirsty's example would make a fantastic episode of a reality TV show about extreme parenting, much like my dad's angst back then, it's merely illustrative of the intensity wrapped up in the father-daughter bond.

"I think an awful lot of men have a visceral connection with their daughters which is unlike any connection they've ever had with anybody," says Joe Kelly, a father to twin daughters and author of the book "Dads and Daughters." "It's just a very mysterious experience. It's also one we never talk about, which adds immensely to the complication of how (the daughter's first love relationship) plays itself out."

"The silence is really intense and then you combine that with 'OK she's now a teenager and she's rejecting me and rejecting her mother' -- that's part of the process. ... And you know how powerful the love from this female has been in your life and now you see it other-directed. It's a really hard transition."

Kudos to my dad for trying to talk to me about his feelings during that life-altering summer. He'd dropped me off at work one day and as I'd stepped out of the car a gust of wind blew my skirt up, prompting me to force it down with my hands. "I'm Marilyn Monroe!" I said with a laugh. Dad told me a few days later that he burst into tears as he drove away.

Nice story, Dad, I'd thought, then escaped to my room to lie on the bed, stare at the ceiling fan and listen to very loud Sade music while contemplating Mark's thighs.

Sure, dads make the usual jokes about this phase, about how they'll be sitting on the porch cleaning their guns as the new boyfriend arrives to pick up the daughter for a date. They might tell their friends with a wink and a nudge they're imposing a no dating rule until their daughter turns 35.

Then there's the whole "men know what men are like" thing. Dads remember how they were at that age: sex-hungry, salivating pimply monsters who see girls as random shapes with boobs attached.

But there can be so much more to it. Especially for dads who have been invested in their relationships with their daughters.

"It's like he got left for a younger man," says Brizendine. "He feels like an older gentleman who's being discarded. And he basically is. We've done our reproductive duty when (our kids) hit that age. We had babies, created the next generation -- now get out of the way."

While Brizendine, author of "The Male Brain" and "The Female Brain," isn't afraid to remind us of the hard truths surrounding our biology, she's all too aware that these feelings are hugely unpleasant. Some of her patients who are fathers are so torn up, she says, they pick fights with their wives out of frustration. They'll even look outside their marriages for comfort.

"Men may be more vulnerable to having an affair as a reaction to this time in their life when the daughter is completely pulling away and he's feeling dissed and heartbroken, and maybe his wife isn't so understanding about it all," she said.

And -- cringe alert! -- a dad's confusion over daughter's budding body could also be a factor.

"Nothing scares a dad more than if for any reason he has any sexual feelings towards his daughter," says Brizendine. "If she comes out in a really hot outfit as she starts to develop and he finds himself reacting a little bit like a guy, he's often just mortified. It's a normal reaction."