This might be a stretch, but it sounds like you'd enjoy the romance with Nicki in
Friends in Need.
It's definitely more the best friends version than childhood friends as the main character is roughly 10 years older than Nicki. The backstory is that you used to work together and were best friends but neither ever confessed their feelings for a variety of reasons.
Nicki can be a little controversial. Without spoiling too much, she doesn't always make the best decisions and there is really a big range when it comes to how sympathetic players feel about those decisions. But even if you feel mad at Nicki, the game does a pretty good job of letting you express that and still have a romance with her. Just to be clear though, it's not NTR as that definitely would not be appealing to me.
And hey bonus points because Nicki is sort of a tomboy. More of the nerdy type than outdoorsy or athletic but I'm pretty sure she is directly referred to as a tomboy at some point.