It's fine, maybe even healthy, to be wary of other men. It's also important to respect your partner's autonomy, and to trust that with that autonomy, they will act in a manner that is healthy for the relationship (and for that trust to be reciprocated). It's great that you are willing to protect your partner, but it's important that you let your partner inform you when that protection is needed, instead of assuming based on your one-sided view of the person your partner is interacting with. Taking action based on that one-sided view, instead of having a discussion with your partner first, can make you come off as possessive.