If high intelligence was that important to you, you should have married someone your intellectual equal. I am sure there is something about your spouse that you love that you value more than intelligence.
I do have troubles because my husband is adopted and his adoptive family are a bunch of ninnies. This would not bother me, except that they are rude, obnoxious, drunk, nasty, evil, disgusting people. They like to push their nastiness on people too. In addition to sitting around the table talking about things like bodily functions, passing gas (except they call it f-a--r-t-i-n-g) and body parts and so on, they like to make remarks about how my husband is so smart and how I have no clue as to how smart and how lucky I am to have him. Ummm, I am smarter than him. My IQ is higher, my SATs were higher, my GREs were higher. I can see in things that happen in our lives too. We have had issues like, where niece was telling my daughter that cello players are stupid and will never do well in life. Then niece went on to claim to be in college classes, including college math. My dd and niece were 11 and 12 at the time, with my dd being older. Niece was really ripping in to DD and bragging and telling DD how dumb she is and so on. In reality, DD is years ahead of grade level and niece is struggling with daily tutoring to stay on average track. She is in a small private school too where they can work with her and give her more attention so that she does not flunk out. My dd tried to tell MIL what niece was saying (remember, niece was really putting DD down for her cello playing and calling her dumb and so on) and MIL just answered with "niece is brilliant and you just need to accept that she is much smarter than you." At that point, I walked over to niece and said "if you have X+2=5, what does X equal?" She did not know! I mean, my 1st grader could answer. She said she could only solve it if she knew what X was. I tried to explain it to her, but she did not get the concept of X being the unknown. She was a 6th grader at the time. Now niece is in 8th grade and struggling with pre-algebra and might have to repeat it next year because she just does not get it. But MIL tries to tell us that niece is in gifted and advanced classes. My daughter was in high school geometry in 8th grade, that is 2 years ahead, she found it easy and fun, and finished the year with an overall grade of 98%.
It is not about needing to compete over the intelligence, it is that they start in on me, or my daughter, and so on. MIL wanted DD to transfer in to nieces school for this year. We tried and looked in to it, but the only way the school could have my daughter was if she accelerated a grade, because they had never had a child who had been ahead of grade level before and were not willing to let her be a 9th grader and just go over to the higher level science and math courses. DD does not want to accelerated, and frankly, when you are talking a school full of average and below average kids, you are not likely talking a challenging school, especially when they admit upfront that they have never had anyone ahead of grade level before.
MIL acts like niece is her daughter and she is a catty mother from the playground trying to one up us. I never tell MIL anything. My children just got their PSAT scores back and they did quite well. It is not the official 11th grade year test, yet, they did very well (94th percentile for one and 99th for the other, meaning, when they get to 11th grade, the one only needs to raise his score by 1 percentile to get commended status and the other will be a semifinalist if her score remains the same. It is a pretty good assumption that it will go up. But even if it went down a few percentile points, she will still be commended).
On the occasion that we have dinner with them, the conversation always seems to revolve around things I would have expected in the 3rd grade. Literally, they seem fascinated by sounds the body can make. They use foul language a lot too. I am suspecting that the issues are largely character issues, but the intelligence things does seem to be there. They don't get or comprehend a lot of things. The bragging they do really bothers me too, even though I know I should not let it.