No offence, but you're mums probably a fair bit past her best, not the lovely shagable bit of stuff she was when they met. So you're dad is missing a bit of nice young ass, now i presume you dont want him to have an affair or anything, again no offence but he's probaly fay and ugly now anyway, so is it not relatively harmless for him to look at internet stuff at least you know where he is, i would try and keep it under control in a more subtle way, otherwise he'll get even more depressed.
Just make a few subte hints about the dodgy stuff and give a few general guidelines in a none obvious way
Anyway let me know how he gets on
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i for one have seen a website of a young lady frm wales who seems ery friendly and willing to please (just like wives used to be), youcan even log on to her sie and book a session, (cough: umm councelling session) she was even kind enough to go on tour visiting hotels that may be more convenient for her clients.... i mean patients.