I want my boyfriend to myself for my bday weekend
Why do you want your boyfriend to only be with you for the weekend?
I guard my relationship jealously as I'm afraid of losing him
It's understandable that you would want to spend time with your partner for your birthday. However, you should not expect to have your partner to yourself the whole time. Being jealous can ruin your relationship and make your partner feel stifled.
That's a highly doubtful theory and I don't agree with it. If a person love me then there's no way that person will get a chance to kiss another person.
I agree with you that your boyfriend should not be kissing other people, and if he truly loves you, then he won't.  However, you should not try to control his every movement, as this will just make him want to get away, and possibly end the relationship.