Can we talk about Tarzan playing with the baby gorillas? Good, because we're going to.
One moment, Jane is playing with them herself; the next, they all see Tarzan and scamper over happily and he plays with them, quite enthusiastically too, he's obviously a regular as far as babysitters in the herd go, and then he looks over at Jane and beams.
Now whether or not he did this on purpose, do you know what male gorillas do to impress prospective mates? They gather fruit. They posture and show off. And they play with baby gorillas to show off what good fathers they'd be.
Jane probably knows this. So you sort of can't blame her for looking at him like that. Ow, right in the OTP.