
I don't get why they should pretend as lovers? Are they just fuck buddies? Or are they not in a relationship yet 0_o

From what I've gathered, no they are not in a relationship, they are indeed fuck buddies (or something along those lines), she proposed the idea of being pretend lovers because her relatives would shame the mother for her daughter not being married. Although the mother says she does not care, the daughter does not like seeing her mother being ridiculed, so she got a "lover" in order to shut the relatives up (=・ω・=)
This is the first time I saw ugly bastard tag in Yaoi 0.o