I am sexually aroused by men but not women. Yet I am still attracted to women and can imagine a future with them but not men. What does this mean?

It's possible to have different sexual and romantic orientations. It sounds like you're sexually attracted to men and romantically attracted to women. For example, if you're a man, you might consider yourself homosexual and heteroromantic. If you're a woman, you might consider yourself heterosexual and homoromantic. Do your research, maybe experiment a little, and definitely find someone to talk to if you need it!

You should do whatever makes you happy. Its okay to be arpused by men, but that doesnt mean you have to be with them.

Sexual and romantic orientation are separate concept that often coincide, but not always. In your case, based on what you said, your orientation is heterosexual and homoromantic if you're a woman, homosexual and heteroromantic if you're a man. There is nothing wrong in who you are, and it does not necessarily have to make your life difficult. You can engage in purely sexual relationship with men if you wish to do so, and/or engage in purely romantic relationships with women. What matters the most is that you are completely honest with your partner as to what you can offer, and make sure they are ok with it. Some people in your situation have engaged in romantic relationships where the partners let each other free to have sexual intercourse with people outside the couple while being in love with each other only. Other people have chosen to give up on one of the aspects, the sexual or the romantic one, and still live happily. Many types of choice are possible, and you can find your own and live happily!

It means that you just need to take time to figure out who you are. I, personally, am sexually aroused by both men and women but I know that I can imagine a future with only men. Yet I know I'm bisexual. Sexuality is like a spectrum, and it's hard to pinpoint where we land on it. It might take a couple tries before you find exactly where your spot is and that's okay. It's not wrong to figure yourself out. But remember that the only person who can tell you what this means is you, and you alone. Good luck!