Is it normal that i can't love people for a long period of time?

I know a lot of couples and friends who have been together since forever - however, I can't understand that, because I can't stand one person for a long period.

I can probably name the stages of friendship for me:
Interest - the stage of understanding a person- friendship- and here comes abruption.

I really can't be anyone's friend for a long time, it is not even important that I had great moments with this person and really enjoyed our relationship, he/she starts to irritate me and I begin to see the great difference between us, even if I didn't matter to me.
The same situation is with romantic relationships, but the terms are even shorter. IIN?