Figuring out your sexuality can take a long time, and it’s normal to feel confused or unsure sometimes. It’s possible you simply aren’t sexually attracted to your partner, even if you’re emotionally attracted to him. The two don’t always go together, and it doesn’t mean there’s something wrong with you. Sometimes the attraction can build in a relationship over time, but sometimes it doesn’t. Depending on your relationship history, you might also be feeling this way because you’re not completely comfortable with your partner (even in a subconscious way). Our bodies react in lots of ways to even subtle forms of discomfort, and your body might be telling you that you’re not quite ready to be intimate with this particular person.
If you don’t think you’ve had sexual attraction to anyone before, it’s possible you’re asexual. Asexual people often feel romantically attracted to others; they just don’t have the desire to express their feelings in a sexual way. It’s also totally normal to go through periods of time in which you don’t feel sexual feelings, and then periods in which you do. Sexuality can change as you go through life due to a variety of factors. It sounds like you and your partner are doing a good job communicating about consent, so keep it up! Remember to let your partner know what you’re comfortable with (and what you’re not) as you continue to explore your sexuality.