My husband and I newbies to the lifestyle in which we have came across the same scenario. One of the couples we have met I'm not really attracted to the male but he is a great conversationalist which has changed my outlook on him.
Different people, different sex styles, different body styles, different experiences and possibly new friends; in my opinion is what the LS is all about. Not comparing someone's physical appearance to my partner/spouse, that is sending a red flag that you may be looking for a replacement of your boyfriend and not just a sex partner.
The other red flag is that you have NOT talked with your boyfriend about your thoughts and feelings - this is the worst thing to do in any relationship - complete honesty and communication are the key in ALL relationships, need it be friends, lovers or family.
My advice is: yes you may be picky but it seems that you need to look within your current relationship before you decide to move forward with the LS.