Let me just add a couple more points before I turn in for the night:
I'm not sure if I am accurate, but it seems as if you are asking whether a person can become a baptized JW without accepting all of the official doctrines. The answer is a resounding NO. To become a baptized JW, you must accept all doctrines regardless of whether they make sense to you or not. As a JW, you must also submit to all organizational policies which can govern many areas of life (healthcare, employment, etc.)
I don't know how much you have studied the Bible, but I strongly recommend that you learn as much about it if you can (if you haven't already). Study the Bible independently of Watchtower publications. I am going to go out on a limb and guess that your boyfriend didn't know very much about the Bible before he studied with the Witnesses. I'll tell you why I say this.
I have noticed over the years that people who have a good understanding of the Bible; and who regularly study Bible commentaries, lexicons, and varying translations almost never become JWs. This is because most of them quicly notice the peculiar alterations of the Watchtower's New World Translation. They often see how the Watchtower has taken various verses out of context, has twisted certain texts, and has even altered the translation of text to create different meaning. People who don't know very much about the Bible, and who aren't very intellectually curious usually won't pick up on these subtle factors.
Doing in-depth reseach into the Bible is very time consuming, and takes a lot of effort. Many people simply don't do this. It is easier to just study publications that tell them what to believe. This is where many people have been mislead by faulty Watchtower reasoning. I myself fell into this trap.
You'll need to do some research on your own. Don't just take our word for it. You need to be convinced yourself.