any good yaoi mangas featuring a middle-aged tsundere seme (cold and reluctant at first, b...

http://www.mangago.zone/read-manga/yume_musubi_koi_musubi/ here ya go this is probably exactly what you're looking for if you haven't already read it.
http://www.mangago.zone/read-manga/kiraboshi_dial/ I don't think there's a big age gap but the seme is kinda anti-social and socially awkward and uke helps out with all that. This author rocks too. :)
http://www.mangago.zone/read-manga/shizuku_hanabira_ringo_no_kaori/ persistent uke resistent seme...
http://www.mangago.zone/read-manga/tenki_yohou_no_koibito/ oh here ya go and its hilarious...
http://www.mangago.zone/read-manga/koi_made_hyakurin/ yakuza story too *a fluffy one though*
http://www.mangago.zone/read-manga/110_ban_wa_uketsukemasen/ cop partners story...the seme is the older more experienced one and I think he might be middle aged...certainly 30s

http://www.mangago.zone/read-manga/majouu_school_days/

http://www.mangago.zone/read-manga/udagawachou_de_mattete_yo/

http://www.mangago.zone/read-manga/hananusubito_kaneda_shoutarou/

http://www.mangago.zone/read-manga/maigo_no_kare_to_kuma_no_onegai/

http://www.mangago.zone/read-manga/dounimo_nannai_soushi_souai/

http://www.mangago.zone/read-manga/gives/

http://www.mangago.zone/read-manga/kiraboshi_dial/

http://www.mangago.zone/read-manga/shouwaru_ookami_ga_koi_wo_shita_rashii/

http://www.mangago.zone/read-manga/rutta_to_kodama/

http://www.mangago.zone/read-manga/koibito_kijunchi/

oh, it's not middle-aged seme, wwwwwwww

Thanks a lot for all the gr8 recommendations, everyone! ( k_brooks: the mini descriptions after each link were really helpful, lol; nickname: no worries! i'll check out the mangas u suggested anyways - they sound pretty interesting :))

You think the seme in Yume Musubi Koi Musubi is middle-aged?

well no I think he's 30 at the most but I think for some readers that might count

or if they maybe just wanted an age gap story...

you're welcome :) I hope you like them

I pegged him as mid-twenties. It made me a bit surprised since I tend to think of middle-aged as mid-forties to mid-sixties.

Hmmm yeah I guessit depends on the person and maturity level, in my brain some people just act older. And the maturity levels different made him seem older than he was maybe. Like I know people in their 30s who seem middle aged and people way older who dont...I thought he was in his 30 I should reread apparently.
I also thought maybe she was looking for an age-gap.