BIL is a bit serial womaniser; three failed marriages by 26 and a near constant stream of girlfriends since then. He's very selfish and immature so they never last. He's in the army, and recently found out he's to be posted abroad for two years. He's been with the latest girlfriend for no time at all, but I know she'd like to go with him and has dropped constant hints about marriage. BIL adamant it won't happen.
More recently she's made a few comments about feeling she's the age to start a family, asking to take my DCs out and saying the timing would be perfect as BIL would have to marry her
I'd mentioned her comments to DH as I thought it a little desperate and strange - BIL does not see the relationship as serious and I've heard him tell her so.
Fast forward to today and she's announced she's pregnant. BIL seems surprised and told DH they were being careful. DH suspects she may have been intentionally less careful and wants to tell BIL about the comments she's been making. I think we should keep out of it and that it won't end well if we interfere. Who is BU?