Knowing if your friend's husband is attracted to you can make the difference between being an excellent friend and becoming a home wrecker, because you didn't do anything about your growing suspicions. After deducing that your friend's husband is attracted to you, you should always tell your friend about your growing doubts of his loyalty. If you find yourself as the subject of your friend's husband attention, checking signs can help you figure out if he is being friendly or flirty.
Read any text messages that he has sent you for red flags. In recent years, text messages have been used to secretly get in touch with someone without letting other people know. If the topic veers toward flirty do not respond.
See if you and your friend's husband show up at the same events or parties. Deliberately mention to your friend that you will be going to the party. If he ends at the party, then you can test his attraction. Do not be overly friendly with him.
Check for obvious eye contact and smiling. Move to a different room -- if you and your friend's husband are in the same room alone. Show him non verbally that you will not reciprocate and he may stop without causing any harm.
Check to see how he acts around you when your friend isn't around. If your friend's husband is attracted to you, then there will be a lot of touching, grazing or rubbing, which are all forms of flirting. Attentiveness is another key part of attraction; check if he remembers minor facts about your life or a story that you told. Don't lead him on. Be direct and not flirtatious.