Are gay men capable of monogamy?

[EvenOlderButWiser]

So here's the story so far, with apologies in advance for the lengthy message!

I've been with my current partner almost 8 years. We've lived together for the past 7 years in the house I own. There is a 10 year age difference between us (may be relevant) Like most couples we have our ups and downs, but always work things through and everything is OK. At least so I thought...

I've always traveled internationally with work and Im currently on assignment in Africa. We talk almost every day and I get home every 2 months for a couple of weeks, or my company pays for him to come out to me. I've been on my current assignment for 7 months, and been back to see him 3 times, including two extended vacations that I paid for.

The last time I was back (almost a month ago) something didn't feel right. You know that little voice in the back of your head that says somethings up but you don't know quite what. It was silly things really; The house was clean from top to bottom (something he never does) which was a bit of a surprise, but then I notice that personal stuff of ours like pictures of us with my kids and mail with my name on it and the like are out of sight, and the bed is stripped bare and everything is in the laundry. Even my personal stuff from around the bed was all put away in the closet (again very out of character for him) It kind of felt that any sign that it was a shared house had been removed, any trace of me hidden away from the casual observer.

I should at this point add that a few years ago I had some trust issues with him, and he admitted cheating on me with multiple one night stands. It was a long time ago and while not forgotten it was water under the bridge and has never been a concern again, until now. We previously have had the long talks about monogamy, and civil partnership etc, so he is very clear where I stand on cheating within the relationship.

I tried to sit down with him before I left to return to Africa, to discuss my concerns, and he totally lost the plot, screaming and shouting at me and generally being very verbally abusive. I know it was quite an emotive subject to talk about but his response was, I thought, totally out of proportion. I had to leave a few days later with things still unresolved and a very frosty silence between us.

I tried to talk to him when I got back into Africa, however he ignored all my attempts to speak for almost three weeks (there were a few text messages in-between) When we finally did talk he neither admitted or denied that he was sleeping around. In fact the conversation developed into one where he told me he was having problems at work and getting depressed with me being away etc etc. (First I'd heard of it) If Im honest, it felt like he was simply putting up excuses for why he did what he did.

Obviously I love the guy very much, especially since he's been part of my kids and my life for the last 8 years. But I feel if I don't deal with this issue of him cheating on me now, especially since he knows that its supposed to be a monogamous relationship, then the pattern of him cheating may well continue. The situation isn't helped by the fact that Im 5000 miles away on a different continent. Maybe he thinks "out of sight, out of mind" makes it ok, but Im really hurt by his actions and that ugly issue of trust has raised its head again, and I think we all know where that can lead to if unchecked.

Can gay men be monogamous when there are so many miles between them, or is there an inbuilt lust to get out there when they have extended separations from their partners?

Should I accept that its acceptable behaviour while Im on assignment, or should I confront this head on, with the possible outcome being the end of the relationship?

Thanks for reading this far. All comments (good and bad) gratefully received.