Right, got you. I'd certainly agree that having other friends to confide in and discuss issues etc is absolutely normal and healthy. That may not have been clear from the above comment alone but I'd written a very long one above and didn't want to repeat the content.

I think most of us over a certain age know when we're approaching that line where a regular friendship begins to have a feeling of being deeper or more significant than it perhaps ought too. A wise person who wishes to protect their relationship will redirect course at that point, a person only out for their own gain will not. We pro-actively protect what we value. A person with integrity who is genuinely committed (in the sense of loyalty not law) will not allow a situation to arise that threatens their established relationship in the first place.

There's certainly nothing wrong with having an attraction to another person whilst in a relationship, but when our actions don't prioritise protecting the relationship over our indulging said attraction under the disingenuous guide of friendship, that's when I'd suggest it begins to creep into the realms of emotional infidelity, ponder it gets to hiding texts and telling white lies it's generally a downhill slope to breaking someone else's heart.