Christ Centered Gamer

Hello it's been a while since I posted on this forum but I have some questions and so I though I would come here. So my cousin is coming in from out of country and so we will be able to play together on something(before we couldn't because of time zones). For some of the time I will be with him physically but not for the whole time so we want something that can to online co-op. We are both interested in Skyrim and wanted to play it so I started looking into the array of Skyrim multiplayer mods.

So my question to you is are there any Skyrim multiplayer mods that would let me and my cousin play in co-op fairly seamlessly?

We are also open to other co-op games but we like the feel of Skyrim. We have an mmorpg (Tera) in line if worst comes to worst and we have to play that(not that its a bad game but we want something more like Skyrim). We have also tried a plethora of sandbox games but we would like something with more of a campain. In all Skyrim is like exactly what we want but we want to play it together.

Edit: He has a mac so we will also have to jump that.

I have yet to try it, but Tamriel Online (Not to be confused with Elder Scrolls Online) is the most up to-date multiplayer mod out there.
It does however require Visual C++ redistributable 2015, which is for Windows PCs, so I am not sure if it works with Macs. (might be a work around.)
And while this mod has gone further than any other multiplayer mod, (to my knowledge)
it's still not completely finished so there could be lag, or odd glitches, etc. (Also there are stable builds and unstable builds, etc.)
Oh and as usual with mod sites, be careful when browsing. (Not that I needed to mention it, I am sure.)

As for alternate game... Lord of the Rings Online is a neat game, but yeah it's indeed not Skyrim.

Thank you. I think we have given up on the skyrim thing with my cousin but i will be playing it on my own at some point. I have sunk many hours into lotro but I am tired of the tab-tab combat system. Thanks for your help though.