can a married man and married woman be more than friends

I am married for last 6 years. My husband of 6 years is a nice sweet person. we both are very attached to each other and have a kid of 4 years, whom he dotes on. Of late I have started seeing him talking very often of his one particular"close friend" whom he was an excolleague but now have not met for years. they seem to be very close, however i dont feel nice asking my doting husband about her. I too find her extremely attractive and hot and have told my sweetheart for which he has a very sheepish smile almost appearing to me as if he is victorious to have her as his friend. I am now confused should i assume he is in love with her, because I have caught him (he doesnt know this yet) seeing her snaps repeatedly very often, i also dont want to be stupid in asking him if there were to be nothing beyond friendship. I am also aware she is happily married. if yes then why does my husband see her snaps regularly.