I am becoming increasingly frustrated with my DM and the way she portrays her marriage as the most perfect and romantic love story with no thought for the pain and suffering she's caused. Basically, a couple of years ago my mother left my father for my now stepfather, after an affair that began in 2009. Although they originally cut off contact after their spouses found out about their infidelity in 2011, after three years they 'couldn't help' contacting each other again and decided to run off to be together.
I was 18 at the time and had not long left home for university, but was basically my DF's only emotional support for at least a year afterwards, despite being several hundred miles away. With regards to my mother and stepfather, I've tried my best to be supportive and form a relationship with my new stepfather and accept them as a couple - we're going on holiday together in the summer, I was MOH at their wedding and I do actually like my stepfather as a person. However, I do feel like I was forced into being supportive too quickly and that if I'd expressed anger or refused to accept my stepfather I would have lost the relationship with my mother entirely - especially as I was told that DM had said I was one of the things she was willing to 'give up' to be with him 
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I honestly think I would be much happier with it if DM wasn't so 'in your face' about it all the time. When I visited over Christmas they had purchased a new artwork - a canvas with words and dates that were important to them and it had in large letters FINALLY TOGETHER! in the middle and the date they ran off together next to it. She frequently posts on Facebook that he's the 'most important thing in the world' to her and really revels in it every time someone calls them a nice couple or such like. They have new jobs working together and their colleagues and other new friends they've made have been told a highly edited version of how they met (along the lines of "oh we were together at uni and had such a spark but then lost track of each other for 30 years and KNEW we were meant to be") with no mention of the other people they were married to at all.
She doesn't tell this version to save face but so everyone will think they are the 'perfect couple'. I understand that this is the way things are but these constant reminders of quite how they started their relationship are still a little hurtful, even three years later. If they could just be quietly in love and not constantly telling me how glad they are to have found happiness in other people's pain it would be so much nicer.
Happy to be told AIBU though and that I should be totally over it after three years - would give me some more perspective!