I'm hardly a model of success so take anything I say with appropriate weight.
The site is very clear about what it does and looks great. If you have the ability to map a finger in front of the camera to a heart beat that's kind of cool. Seems a bit trivial and useless thing to do to me. However like I said I'm not a model for success and I am 33 year old man / programmer, I still don't understand the success of Instagram, Twitter, cat pictures or almost anything on the internet.
You indicate this will be available for iOS/Android/Windows. Is that necessary? Why not just do one to see if you have any traction. Are you doing this to make money? If so, your pricing seems very low.
I would never use it but I'm not a teenager in love or in a long distance relationship. I'm married with two kids.
A unique idea and wish you success. Just take it easy and focus on one platform I say unless you have friends working with you on different platforms or funding, just don't want to see your burned out like I've been before. Have you got any indication anyone is interested in this?
EDIT: Just noticed the first thing you said is it's bootstrapped. So yes definitely think doing three platforms is a bad idea. Are you doing all that other stuff too? Video, messenger? I can't see how you could run a service like this bootstrapped for that price. Biggest thing: any indication anyone is interested before you develop, any beta users?