you are mixing up 2 different things.
1: Are you sure that they are in love?
2: are you sure that the guy/girl who is not competing is not in any kind of complex?
if you love someone then i guess every sensible person will give a try .. For sure! but if you have some kind a complex compared to the “other” person you are competing to you then you will try to come up with random reasons of not competing or this n that 