Is this Midlife Crisis or is he really being sincere?

I am 25 and my boyfriend is 40. Both of us have never been married or had any children. we are very compatible with each other and have a lot to keep this relationship going. Now people say the 15yr age gap is too much but i don't mind. It has never really occurred to me in our interaction that there is a significant age difference. I also know at this stage in life that some men go through a midlife crisis. Would he be a perfect example of this? i know that John Mccain was exactly 40 when he married his 2nd wife Cindy who bore him 3 children. I just don't have an inheritance or come from a very wealthy family like Cindy Mccain did. All i have is my brain, my intelligence and the beautiful heart that the lord has blessed me with. My boyfriend on the other hand wants to put me through law school which is something i definitely want to do.