Otherwise friendship is far more difficult to acquire because with a romantic relationship there is mutual gains: attention, compassion, sex etc.
Friendship is more difficult because there is no direct benefit from it. Why would you hang out with someone if you don't benefit from it directly? A lot of friendship are formed during childhood because people bond over mutual experiences, it's harder to do that as an adult.
By contrast, if you're a working man and you take care of yourself (both physically and mentally), getting into a romantic relationship won't be hard. Getting out of it is the difficult part.