@Ceaserofnone
Like others have mentioned polygamy isn't the answer. It'll just be multiple women disrespecting you. You mentioned you let your body go somewhat, and now the natural repercussion is your wife isn't as attracted to you. Your investment of energy in hostility and irritability at her behavior is misplaced. You're attempting to force when you should be inspiring her through your own personal achievements.
your energy should be going towards building your body and mind back up. Don't ever mention her wondering eyes to her again. Give her enough rope and see if she hangs herself. Simply start working out and preparing for the single life. Get chiseled, focus on fun hobbies, meet new people, new women. You don't have to flirt with them but keep them in your social circles. Your wife will either be sweet and want to spend more time with you or she'll complain or fool around. She will polarize herself as either a loyal loving wife that wants to work on building a life with you or a two faced toxic woman that really doesn't want to follow you. Either way you win.
when you've worked on yourself enough her behavior will seem so trivial and useless that you'll be waiting for the one year mark to hit. Your thinking will be 'i dare you to eye other guys and try something', not out of hostility, but because your sense of self worth will be revived. You'll be easy going and care free(since your pursuits are much harder by comparison to a bit of relationship friction), and even your friends and family will comment on how you're too good for her. if she's smart she'll sense this disengagement and get her sheet together. If she stays distant let her be distant. Focus on cultivating a fun personal life. If you're horny go for a run or go lift or go do something social, let her initiate all sex for now.
For me if a woman isn't asking about something, I don't bother explaining it. In my experience unsolicited advice falls on deaf ears with a girl. if she's not curious enough to ask, then she doesn't care enough to listen and follow through.
If you really want to wait a year before breaking it off then treat it like a boot camp to mold yourself into a stud for the sexual marketplace so that you don't miss a beat when it happens. The boot camp should never really end btw, make it a lifestyle.