this sounds like a fair approach - a shotgun clause right? i feel emotionally invested in the product since it was my idea, but he put a bunch of time into it and we both believe in it.
we've both contributed equal time to it, using our different skills. he's written more of the code, but the designs are mostly mine, and i've done all the research into advertising, CTR, managed our intern, and done the biz admin.
Ideas often aren't worth as much as execution.