My 4-year-old has a crush?0?

My daughter is four years old and is the best part of my life. �We have a close relationship and we spend a lot of time together. Recently, she has been spending more time with our friends' children which means less time with me. �That's fine because I wouldn't want my little girl to grow up friendless and lonely. �That is, until she starts playing with this little boy that is the son of my wife's best friends (both of whom I cannot stand). �She always is kissing him and hugging him and he's always hugging her and they have little marriage ceremonies. �My wife thinks its adorable but it pisses me off. �I know I'm overreacting (even though that kid is a little troublemaking brat) but I have no idea what to do with this situation. �I don't want to deny my daughter her friends but that little brat is crossing the line. Would I be ridiculous to not allow them to see each other? �I've talked it over with my wife and she trusts my judgement as I see our daughter the most but I have no idea what to do. �Am I just being an overprotective ?