This question points to the classic dilemma of having to choose between form and substance. When dating, it often is not easy to find people who meet both your physical and non-physical needs and desires. There is a lot to be said about the virtues of having reasonable expectations and being able to make some compromises, but there is also wisdom in knowing when something will not work for you despite your noble intentions or rational assessments. Sexual attraction, unfortunately, is not always compatible with other traits that you find desirable or endearing in people. When issues of sexual attraction are involved, the dilemma can be a struggle for even people who are far from shallow. To whatever extent penis size matters to you, only you can decide whether the issue will be an insurmountable obstacle for you in establishing and maintaining a successful relationship.
I dealt with this very issue once myself. Years ago, I was romantically involved with a great guy who "punched all the wholes in my ticket" so to speak, in respect to both physical and non-physical considerations, other than he had a small dick. (I prefer sexual partners who are some shade of well hung, although an average endowment is perfectly fine, as long everything else works for me. I do find small dicks, however, to be unappealing, and this guy was small enough to be disappointing.) He was enamored by the size of my cock, and I assured him that him being on the small side did not matter to me. I loved him, and most of me meant what I told him, but I would be lying to deny that there was always a part of me that wished he packed more between his legs than he did. We were only together for eight months, so I honestly do not know whether his small penis would have eventually become a problem for me. I like to think not, but I am not totally sure.
My partner and I have been together for years, and there are many things other than sexual compatibility that contribute to our successful relationship. Nonetheless, I know one reason that it works so well is that we are one another's physical type, and as a result, we can maintain our sexual chemistry. Yes, he is well hung, and I have been blessed with the icing on my cake. It is not all that matters, certainly, but it does matter; perhaps more than it should.