I turned 50 last May, married and divorced with 2 kids (Twin girls 12 yo), I have custody. Been single for 10 years since I returned from Afghanistan and learned my wife was pregnant with another dude's kid.
I am not saying everyone should be like me and just date around... I know plenty of guys that are in marriages that seem to make it work, but the truth is most are miserable. The reason they are miserable is that they have never learned the true nature of women. They have bought into the feminist narrative and believe there is no difference between men and women. The biggest problem as I see it is that men expect women to act like men. They expect them to be rational and loyal... they aren't.
As for myself, being 50 and dating around.... it's hard.... REALLY hard, I have to work out every day, watch everything I put in my mouth, and it takes a lot of effort being the best I can be. I never stop learning, and I am always looking to involve myself in new things. But the truth is that if you want a long and happy relationship, everyone has to do the same... you can not relax with the women in your life, it takes A LOT of effort, because they are emotional, not logical, and they are definitely NOT loyal. Just yesterday I had lunch with a women who runs an export business, very successful. Before she walked into her office building she grabbed me in the street and kissed me.... yes she is married, to a college professor, with two kids 4 and 2. This kind of thing happens to me all the freaking time. What is happening in that marriage is the husband is getting too complacent.
If you want a long term relationship, you have to be a DJ, because, in-spite of what they say, that is what women want. Then you just don't fool around with other women... which is going to be hard, because if you embrace reality, and these principles, you will have options. Your lady is going to try and change you into something other women don't, she will try and give you that 'Dad' bod, and break your will... so she can have you all to herself. But all that she will do is sow the seeds of her own discontent, because as soon as you become something that is not attractive to other women.... she will not be attracted to you either.... so begins the decent into hell....
Be a DJ, but just don't fool around on a women you are in a relationship with... the truth and principles are the same, but you have to exercise self control, if you want a LTR.