Well to put it bluntly............yes a man needs a strategy regardless of how much he loves a women, as does a women! The fact is temptation is all around us, and for men who typically are sexual creatures its far easier to fall into a affair then one would think.
The fact that he is wanting to prevent temptation is a strong indication that he is less likely to ever fall into cheating. Being faithful to a women isn't about love...........sex is a simple urge and many men separate sex from love so therefor when they cheat on a women it isn't because he does not love her its because he had a urge and temptation got to him.
Many women feel a man can not be faithful...........and the fact is it tends to be true because most men do not set out to NOT cheat. They assume that because they are in love and are happy that they will not. Then when temptation hits them in the face unprepared its harder to avoid cheating. On the flip side a man who is willing to make a plan and a firm choice NOT to cheat can and often will not cheat.
Women also come with the assumption that as long as they are in love they will never cheat..........which is fine theory. But lets keep it real here, women love attention just as much as men do. And when a good looking man starts to flirt with her in a situation where she feels comfortable not getting caught flirting many women will flirt back. They see this as harmless flirting and they will NEVER take that leap to cheating. But the fact is over time that attention and flirting causes a bond and women find themselves in a situation that often involves cheating.
The key for both genders is to go into a relationship with a firm plan.........which for most people is avoiding temptation. If a women shows interest, avoid her. This is not to be confused with you thinking he does not love you.........in fact if he did not have a plan you would have a right to question his motives.
Keep in mind also he is older, and has a little more experience in this regard. It sounds like he has found himself in this position before..........and has a determination to not wind up there again. And that is good!
As for the friend he looked at........he was open and honest with you. I understand it may have hurt your feelings a little and maybe even made you question his faithfulness. But the man is not dead.......even happily married men are going to look sometimes. Compare it to being at a party and a guy wearing next to nothing and dancing around. You would likely feel some small desire to look as well. It is a simple human urge....and nothing more.
The flirting was not a good idea.....and something you should discuss with him. Let him know why you find this unacceptable and request that he not do it in the future. Some men simply do not take the time to think about what they are saying and I think it boiled down to a bad judgment call instead of a view of his morals.
Many men are not ready for a long term relationship and thus they do not plan for problems..........and those are the men who typically cheat. It sounds like you have been blessed with a guy who is willing to work for this relationship and that is a real blessing in the end.