Hi bro,
This is quite a multi-factorial question and I think relationship fatigue does fluctuate. My ex can irritate the hell out of me by being terribly insecure and sticky but melt my heart the next moment she does something sweet. But I do think that constant exposure to the same problem, for instance insecurity, can wear the other party out really quickly and cause some permanent scars. Without going into details, I do think that it really varies based on the dominant situation factors. Attention on other girls? Haha...always there and most of the time, regardless of the state of relationship. I mean, which guy doesn't look at girls and indulge the mind from time to time?
I am curious: Why did you ask? Hope you are not facing relationship problems.
And yes, I do hope that the girl pulls the plug and I have been on the ‘losing end’ on several occasions by agreeing to the request. It’s an easy way out, isn’t it, thinking that it’s the girl that wants out and hence, you shouldn’t feel too guilty. Sounds terribly familiar! Is it a common practice out there?