Evaluate your environment once you are inside. Say you are going into a coffee shop that you have been in a thousand times. Don't assume because you're familiar with it you know the lay of the land. Review the landscape; it could change.
For instance, there could be a repair crew performing some wiring so an exit is closed off. Evaluate where bad guys can enter and where you can exit out innocents or effect an escape yourself. Do not stick to the public entrances! Consider fire exits, kitchen exits, staircases, etc. Evaluate. Don't just look.
While you are there, use all of your senses. You continue to observe, not just glance. You listen for sounds, distress, screams, shots, or whatever. Your touch/skin will sense changes in temperatures; maybe a window has been left open or a door is ajar and you feel a breeze. Stay aware and not sit there like a lump on a log.
Discuss your situational awareness with your guests. If all is well, I tell my wife that I like this place for it is quiet or has good food; by this code she knows I am settled in. However, if there is something or someone that has your dander up, tell your spouse or whomever you're there with.
For instance, if a couple is having a heated discussion and I feel that a domestic dispute/violence could break out, I make notice of the couple at my 2 o'clock (her 8 o'clock) of a possible issue. Here I make the call to contact the waiter 9-1-1, or just politely reposition ourselves. If this appears to be too insecure of a scene, you may wish to exit.
I see no reason to jeopardize your loved one. Repositioning for safety is an option. There are other responses but the key here to your safety and your family's safety is awareness. Sitting and pretending nothing is going on is what I call "ostrich management," and if you do so you should be prepared for exposing your butt to the wind.
If you decide to send out your guest so you can observe or to allow the guest time to exit before something could happen, give instructions. Here is the key: Go as if you are leaving but wait at a store across the street (rally point). Never let things just happen. A good strategy pays off.
In looking at your environment stay aware of what changes about you. As you exit be aware of who is behind you. You could have been recognized as a cop and the assault may come at your departure. Always think 360 degrees.
I'm not the one constantly looking for evil or the fight. However, planning and preparation will overcome panic if something happens.