Well Ignorant, your post is a pretty good summary of what culture does to men and why so many men generally hide their bi curiosities until the right opportunity surfaces.
Most guys are afraid of exactly what you describe - that someone they love or care a lot about is a homophobe ! And that showing ANY attraction/curiosity to the same sex - even if it's strictly for sexual variation - is going to start a landslide of negative feelings & associations. One that will destroy any attraction they might have for you.
All I can say is that I feel you should do some analysis on your homophobic feelings. See if you can better understand where they came from - and if it's in your best interest to hold on to them. Human sexuality is very broad and a majority of people - male or female - have some bisexual tendencies. Whether those curiosities get explored or not depends on the person and their situation. But if they don't, they can become hidden points of resentment if it's felt that someone else is the roadblock.
But it seems the genie is now out of the bottle and whether your relationship will grow or deteriorate will now depend on you !