I read something maybe 2 or 3 years ago that I thought was ironic. The interviewer was talking to a female porn star and she said she hoped her film partner thought she was attractive. They’d had sex (but that’s what they’re paid for) and in the scene he seemed to like her (but maybe that’s acting) and he certainly was hard (but maybe that was Viagra). It seems like a lot of people want others to like them a lot, enough to have sex with them…but they had already had sex. She wanted him to find her attractive.
In Carrie Fisher’s final book, the memoir The Princess Diarist, she discussed the affair she had with Harrison Ford (who was 14 years older than her, and married) during the filming of Star Wars. She noted that it was considered to be very common for actors and other members of a production team on film sets to wind up having affairs during filming, especially if the shoot was away from home.
Fisher also described how she (who was 19 or 20 years old) fell in love with Ford during the affair, while he seemed to feel it was much more of a casual sort of thing.
For how long? That ‘article’ is from 2017.
They’ve been together since 2016 and became engaged in 2017 according to what I just read.
You think you’re kidding but
Gellar And Boreanaz Used to Eat Gross Things Before Kissing Scenes
Both David Boreanaz and Sarah Michelle Gellar loved to pull off pranks on one another during the filming of the show. One of their favorite things was to gross each other out by eating all sorts of stenchy foods before kissing takes. “The unsexiest thing in the world,” said Gellar Back in a 2002 interview with The Independent. “[We] were the worst. We would do horrible things to each other. Like eat tuna fish and pickle before we kissed.
Isn’t there a sort of stage kissing where you only sort of pretend to kiss?
In The Making of Star Trek (1968), William Shatner describes how he fell in love with his first wife, actress Gloria Rand (note the name!), while they were kissing in a play.
You must remember this.
A kiss is just a kiss.
A sigh is just a sigh.
Don’t assume that the shot of him appearing flaccid is from the same take as the shots of all the grunting and heaving. And don’t assume that because his genitals were uncovered in shots where you saw them, they were also uncovered in the shots where you didn’t.
When I was 18, I played Henry Higgins in a production of Pygmalion. Eliza and Henry are supposed to have fireworks, and we seem to have inspired each other. My castmates and friends remarked on how much chemistry Eliza and I had. Funny thing is, I felt nothing for her, neither attraction nor dislike.
That’s show biz.
I think it comes down to practice. Most actors that you actually see in romantic situations probably have lots or opportunity for romance. Seems to me it would be easier to avoid becoming attached during performance if you’re already dating others.
There is an old quote on the subject where the handsome actor replied, “It was like kissing an ironing board with her mother standing behind her”.
I dunno, when I was younger I would get lots of ‘certain looks’ from men and I got kissed quite a bit by many. I never instantly fell in love with any of them. I am not in show biz, needless to say. Odd it happens to you… If all it took to ‘fall in love’ was a kiss, why aren’t we (mostly) all walking around swooning in a pink cloud of love? (are we?)
I was called in for a filmed audition once for a heavy make-out scene. My partner was someone I knew, and let’s just say we had not hit it off in the past. The director described what he wanted and we both looked at each other like, “Really??” But, we’re professionals! So, off we go, WEEE! Smooch, slurp, squeeze, etc.
I mean, it seemed like it was way over the line for a first audition. Maybe a dialog scene first, yah? And I’ve never struck myself as a romantic leading man type, so I was out of my element, so to speak.
Needless to say, neither of us got the parts.
I can attest that stage kisses, which happens for a role usually much more then movie kisses (due to rehearsals and any number of performances)…for ME…are usually about as erotic as trying to remember your lines.
This is what I’m thinking: “Now where do I go next? Do I know that guy in the front row?”
From my perspective, I can’t imagine why the mere act of kissing someone be automatically connected with falling in love with them.
IIRC, Kim Basinger once described kissing Mickey Rourke as “Like licking an ashtray.” 
Before it was tampered with, Shaw’s play also had no chemistry between Higgins and Eliza.
A possibly-apocryphal tale of Sean Connery says that before filming a sexy scene for one of the Bond films, he told the actress, “Something is about to happen. Or it isn’t. I apologize in either case.”
I saw a clip of Blake Lively talking about watching her husband Ryan Reynolds getting pegged by Morena Baccarin in Deadpool. Apparently, her child reached for the screen and said “Daddy!”, which must have made for an incredibly awkward moment.