Multiple protagonist games can be tough to pull off for a lot of reason. Not least of the reasons is because most players will associate more with one over the other or may even dislike one altogether. Having one be male and the other female adds some difficulty of its own.
If they will end up together then some players may be upset if she has a lot of sex partners before that time, like the game was cucking the male MC (Not saying this is reasonable just that some will feel that way, so you may get hit with people upset about it). It isn't necessarily any better if they never end up together either because then people who kept her from having sex (thus missing content) since you said all the sex scenes were optional may be upset that she never ended up with the male MC while they did all in their power to make it happen.
Another potential problem is workload, each main protagonist needs equal time, or it will seem like you prefer one over the other and then that begs the question of why you made them both main characters to begin with.
This is all just me thinking of this as a fellow storyteller and writer myself (I'm writing some VN's myself right now but still struggle with the 3D art part of it too much to get anything out to the public). I love writing multiple protagonists for my novels but would never do it for an adult game especially. I applaud your bravery in trying to tell a story this way and really do wish you the best.
I would like to try the game out when a few more updates come out, there is a walkthrough, or I see some spoilers about how the two MC's interact and if it is viable to play the game in way to set them up together in a good romantic relationship.
I know not everyone likes spoilers, but I love them, I hate negative anticipation. Spoilers turn the questions of "what's going to happen" and "are they going to make it" into the more positive questions of "how this or that is going to happen" and "how are these characters going to get out of some situation" (and if you know they won't get out of it you can now laugh at all their stupid choices instead of being upset at how dumb they were). It's why we reread books, rewatch movies, and replay games even though we know exactly what is going to happen. Positive anticipation is so much more powerful than negative anticipation.
Sorry for the somewhat rambling post,