Not that I agree with the "Parker is an antagonist" theories, but just playing devil's advocate for a second... Parker already knows what MC's power is and is probably aware that it's only a matter of time before he get's Evelyn's power too... so all she would have to do is avoid touching MC to avoid being host to his scrying.
With that said, whether or not she has malicious motives, she might still have things to hide from the MC due to whatever she's involved in, but the point is that there are ways the Dev could write it to avoid revealing Parker's motives until the right time in the story should MC get Evelyn's power.
I mean yeah it's a porn game. But the point is that if you would rather play it as being exclusive with Evelyn, you could totally do that and just acquire powers through Moonsong's test tube method. IMO, I don't think there is anything to worry about though. I think there are going to be plenty of charming scenes with Evelyn going forward. Just because she's giving MC an unlimited hall pass doesn't make her a less romantic girlfriend... it makes her the best girlfriend!