It's very well organized. :-) I admire your honesty and willingness to share with strangers. I'm new here, but as a philosophy writer I give advice for a living, so DUCK...
The first thing to think about is whether "lust" is a valid concept or a myth. Our culture is very sex-negative and we've all been conditioned to think these low, vile thoughts about ourselves when we're turned on. It sounds like your sexual encounters are not a matter of shallow, physical-only attractions but of an honest interest in fascinating people and the way you feel when you befriend them. Which isn't shallow lust by any stretch of the imagination.
Monogamists have been taught that their partner's sexuality belongs to only them, within certain limits which are arbitrary. The more a person decides to accept this & cultivate feelings of jealousy & possession the stricter the ownership becomes. For instance some husbands "allow" their wives to have platonic guy friends, some truly grade-A assholes forbid them on the basis that attraction may take place.
If you're in love with your boyfriend based on his character and his personality, then it's natural that he's not the only person in the world you are going to find the same character traits in. I don't think any emotional expression, sexual or not, is a real threat to your relationship, unless somebody comes along who you could see replacing him as a primary love relationship, domestic partner etc. And from the sound of it, that's not going to happen.
My best advice is to continue to manifest a free sexuality, because it's a part of who you both are. It's a part of your identity. When you say "I love you," there's not an "except for THAT part of you" attached to it. Be free, be happy, and unless you're having anonymous sex in bath houses I wouldn't cast myself as lustful or selfish.