Ok there's so much of talks about love angles and shipping and fake and real and all that, but in a way it's not surprising that love stories are such an integral part of BB. HMs are staying in close proximity with each other 24*7 and mostly hostile environment where everyone is trying to get the better of everyone. It's only human that in such a place you invariably form a bond. There are other bonds formed too, but I guess a love angle is most common.
Also from the previous seasons most of the love stories have been going steady.
PS: whatever the reasons maybe, but I suppose most love stories in BB do lead to a stronger bond outside like
Asim and Himanshi
Aly and Jasmin
Puneesh and Bandagi
Paras and Mahira
Prince and Yuvika
And of course Sid and Sana.
Of course many didn't last too like
Gauhar and Kushal
Tanna and Upen