Maybe Ophelia is an exception for him!! After all love knows no gender or boundaries,it just happens.
In that situation she wouldn't be an exception, he would be bi, and honestly, I'd rather read friendship, it's way better than a cliche "you thought I was your friend but I was just a sneaky little shit who wants you" I mean can't we just read a genuine relationship between a man and a woman, they're perfect like this
There is this one thing that I find very nice in this manga. It is that ML doesn't try to hide his true intentions from FL. ML wants power through FL and he almost mentions that in one way or another in every chap. So trust won't be the issue here I guess.