In general, the older you get, the less the age gap matters. What makes age gaps a big deal is the fact that two people have different life experiences and life expectations at different ages and making those things work in conjunction is sometimes very difficult. 26 and 22 might not be a big deal or it may be a big deal. In the US, most 22 year olds are just getting out of college and into the "real world" and do not really know what they want in life. At 26, most people have been in the working world for a while and know where they want their career to go and where all other pieces "fit" into their lives. However, that is definitely not everyone. And without more knowledge about your situation and her situation, (other than being long distance), I can't really say if the age difference is a big deal or not.
Just keep in mind that as long as both parties are legal, it is not as much about the age difference as it about the life experience difference.
Good luck.
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