Age span of working relationships

How many years can separate you and your significant other in a relationship? Does it matter? Will age cause you to drift apart at some point in your life if the years are many? I keep asking myself that after the recent breakup of a 12 yr. relationship where I was 16 yrs. older. Was it inevitable? He started playing. I didn't mind, I'm not the jealous type. Have all the friends of any gender or race but don't hide it and then lie to me. If you're ready to move on let me know, don't let me walk by as a private message pops up with a chick's face and tell me she's from a festival site and you're telling her about the next fest. Why can't u do it on the site. Then erase all the messages. When I get my computer into my new home I see there are 40 pm in the temp files for the same girl for the past 4 months. I didn't deserve that or did I? He would say he never gets on the computer and they were all when I was sleeping or away. When I said it was time for me to move he didn't flinch. Pack ur things. Finally he has his out. Maybe it was the age difference. Maybe the boredom. Maybe his salary increase that enabled him to support himself now. It happened so fast and my head spins. He said my love is real, not fade away but it sure turned cold with just some extra cash. What's the most yrs. that can separate a working relationship I wonder as younger men want to date me now? Where do I draw the line? Or maybe I'm just too old period. I'm 51. The thought of starting over is 2 hard to comprehend. Who can I trust now?