MBA for PE Associates

First off, congrats on getting to where you currently are!

I'm a bit biased (currently doing an MBA), but will try to share my perspective on your concerns:

(i) if I do the MBA I would do it with approx 30 years which would mean finishing the MBA with 31-32 (depending on the program): Given your background, it seems you would be going for a VP-type role, which I don't think is unreasonable at 31-32. A bigger concern would be, if you were to do a top MBA in the US, whether you can stay in the states (visa, etc) or dedicate sufficient time to recruiting in Europe.

(ii) opportunity cost in terms of career: It's going to be expensive (both the MBA and the foregone salary). Aside from the intangible benefits (fun, vacation, etc), I'd focus on whether you can develop a solid network in the space you are covering without going to an MBA program. Despite having a few professional relationships outside of PE, and friends working across different industries, I couldn't say I had a meaningful "in" into some of the sectors I would have been covering if I stayed in PE. A b-school connection isn't a guarantee for that, but it certainly opens doors if you are smart about it. If you can be proactive in cultivating relationships with peers and alums while at school, then I think the residuals from that can outweigh the opportunity cost.

(iii) I work in Southern Europe and here the opportunities in PE are limited (even more in Special Situations): Have you spoken to your team to see how they would react? One of my previous firms was very much "2 years and pls leave" to MBA/another place (though some have stayed a symbollic title bump). Other shops can be supportive and let you come back, or may keep you attached while you are at school (I continue to do some work remotely for my most recent shop). If you are serious about staying in the space, try networking with people at those funds and getting their perspective. When I got accepted into my program I reached out to more than a handful of individuals (alums) across funds I was interested in to hear their story and what I can do to position myself for a firm like theirs upon graduation.

(iv) due to personal reasons (stable couple) I believe it is possible to be 2 years away, but then with almost 100% probability I would have to return to my country: Some of my classmates are doing this, it's totally reasonable. Others (despite having started school with the best of intentions) have not been able to balance school/recruiting/non-MBA partner. With regard to returning to your country in a professional capacity, consider how you will navigate international recruiting. Many schools have treks for this where they organize a road show with different employers across the world, so there is some support, but expect to put in a ton of effort and travel time.