I badly need advice before i make a huge mistake about moving in with this guy, please help?

me and my bf are together a year and have a long distance relationship but i recently got a job in the city he lives in so im supposed to be moving up today to move in with him and his family. however we split up for 2 months recently and got back together last week and this morning this random girl he became FB friends with a month ago while we werent together, left him a comment with a heart like this <3 i said it to him and he said he never spoke to her in his life and his mate does be talking to her (his mate does be talking to her as i seen comments but it still makes no sense why a girl he never spoke to would leave a comment like that on his page. im so worried now what should i do, what does this look like to you? please help im very upset and dont want to be made a fool of