Good accurate advice from Sirona.
We did have people in my old congregation who were married to 'unbelievers' but they were without exception people who had chosen to come into the religion after they had got married, and their partner hadnt.
They were regarded as (1) either people to keep at arms length because association with them meant association with a non JW or (2) someone to be sickly nice to because it seemed like there was a good chance we could 'nice' the partner into the religion.
Its not a nice position for either partner to be in and the pressure must be tremendous and relentless. The non JW partner has to be really strong, and in some respects brutal to stop the JW partner from continually preaching to them. Then there is the issue of birthdays, christmas etc Easier to negotiate if there are no kids, but still you will end up going without those celebrations you may have loved.
In your position, if the elders detect you have no interest in converting your b/f will be put under immediate pressure to stop sleeping with you, and then after that to break off with you. If he chooses to marry you anyway without you becoming a JW he will be barred from priviledges.
I was in a position, when I was a JW, where I tried to marry a JW who had been brought up in the religion but just hadnt got round to getting baptised. A meeting with the elders resulted and I was told I was in effect marrying an unbeliever. An announcement was made that no-body should attend our wedding, and we had to call the whole thing off (becuase we only knew JW's - both having been brought up as such). We then had to wait until the elders saw fit to let him get baptised - which they refused the first time because they said he only wanted to so we could get married. So we had to pretend like we werent waiting to get married and just concentrate on convincing the elders he wanted to get baptised.
His life would be much more difficult that this is he went back.