don't think so size-centric when it comes to happiness from sexual pleasure. people rarely leave people because of a specific penis size, guys! quit thinking that a large penis is just in any case a happiness provider for everybody, as large dicks have been left for average or smaller ones too! some wives got so tired of their husband's large dicks, who maybe weren't taking the necessary time and caution or giving the appropriate passion and stamina... while for some a large and thick penis can be a hot and horny "plus" - for others it might just as well be a "minus" as they might be frightened about it hurting or stretching them. if couples separate, it's for other reasons than penis size.
each penis and each man are a unique combination - skilled or not and matching a partner overall or not, no matter what size. "women" dont just want a specific big or small size, they want someone who can provide sexual pleasure with whatever size and that fits for most guys if you recall the scientific 2015 penis size distributions.
no matter what size you are, you have to "read" your woman (or man) to provide the best for that person's needs, otherwise no matter what size you have, you might just fulfil your own pleasure. there lies the secret for happy sex lives guys, you need to use whatever you have in the best way for the needs of your partner, to maximize the pleasure for your significant other, that's the key for fullfilling sex!
penis size does not matter for happy sex - your brain's size does...