It depends on the lady involved. If she is someone who likes sex a lo, then it may probably affect the love his wife/girlfriend has for him.
Some ladies love guys who can last long in bed, if you can't, she may just find someone else who does.
To most girls it could affect their love for their boyfriends or husbands
While to some it doesn't matter their love for their spouse still stands.
In general yes. Girls want their man to be strong and hot in the bed. As a woman I know we finds it a 'representation' of our love and belongingness. So if my man does not show his stamina a way I need, there is a chance that I may not feel the same love with him for long. It will surely affects.
Yeah. Sex life and love life are definitely interwoven. They influence each other from time to time. But stamina of a man in bed? I think it plays a minimal role, especially if their relationship is very strong and firmly built.